Pearl Harbor advance-knowledge debate
Encyclopedia
The Pearl Harbor advance-knowledge conspiracy theory is the idea that the American
officials had advance knowledge of Japan
's December 7, 1941 attack on Pearl Harbor
. Ever since the Japanese attack there has been debate as to how and why the United States
had been caught off guard and how much and when American officials knew of Japanese plans for an attack.
Several writers, including journalist Robert Stinnett
and former United States Navy Rear Admiral Robert A. Theobald
, have argued that various parties high in the U.S. and British
governments knew of the attack in advance and may even have let it happen or encouraged it in order to force America into war via the "back door." Evidence supporting this view is taken from quotations and source documents from the time and the release of newer materials.
Frank Knox
(1941); the Roberts Commission
(1941–42); the Hart Inquiry (1944); the Army Pearl Harbor Board (1944); the Naval Court of Inquiry (1944); the Hewitt investigation; the Clarke investigation; the Congressional Inquiry (1945–46); a top-secret inquiry by Secretary of War
Henry L. Stimson
, authorized by Congress and carried out by Henry Clausen
(the Clausen Inquiry; 1946); and the Thurmond-Spence hearing, in April 1995, which produced the Dorn Report. The inquiries reported incompetence, underestimation, and misapprehension of Japanese capabilities and intentions; problems resulting from excessive secrecy about cryptography
; division of responsibility between Army and Navy (and lack of consultation between them); and lack of adequate manpower for intelligence (analysis, collection, processing).
Investigators prior to Clausen did not have the security clearance necessary to receive the most sensitive information,. Clausen claimed that, in spite of Secretary Stimson having given him a letter informing witnesses that he had the necessary clearances to require their cooperation, he was repeatedly lied to until he produced copies of top secret decrypts, thus proving he indeed had the proper clearance.
Stimson's report to Congress, based on Clausen's work, was limited due to secrecy concerns, largely about cryptography. A more complete account was not made publicly available until the mid-1980s, and not published until 1992. Reaction to the 1992 publication has varied. Some regard it as a valuable addition to understanding the events, while one historian noted Clausen did not speak to General Walter Short
, Army commander at Pearl Harbor during the attack, and called Clausen's investigation "notoriously unreliable" in several aspects.
cryptographic operation in New York City had been shut down by Henry Stimson (Hoover's newly appointed Secretary of State), citing "ethical considerations", which inspired its now broke former director, Herbert Yardley
, to write a 1931 book, The American Black Chamber, about its successes in breaking other nations' crypto traffic. Most countries responded promptly by changing (and generally improving) their ciphers and codes, forcing other nations to start over in reading their signals. The Japanese were no exception.
Nevertheless, U.S. cryptanalytic work continued after Stimson's action in two separate efforts: the Army's Signal Intelligence Service (SIS) and the Navy's Office of Naval Intelligence (ONI) crypto group, OP-20-G
. Cryptanalytic work was kept secret to such an extent, however, commands such as the 14th Naval District at Pearl Harbor were prohibited from working on codebreaking by Admiral Kelly Turner as a consequence of the bureaucratic infighting in Washington.
By late 1941, those organizations had broken several Japanese ciphers, such as J19 and PA-K2, called Tsu and Oite respectively by the Japanese. The highest security diplomatic code, dubbed Purple by the U.S., had been broken, but American cryptanalysts had made little progress against the IJN's current Kaigun Ango Sho D (Naval Code D, called AN-1 by the U.S.; JN-25 after March 1942).
In addition, there was a perennial shortage of manpower, thanks to penury on one hand and the perception of intelligence as a low-value career path on the other. Translators were over-worked, cryptanalysts in short supply, staff generally stressed. Furthermore, there were difficulties retaining good intelligence officers and trained linguists; most did not remain on the job for the extended periods necessary to become truly professional. For career reasons, nearly all wanted to return to more standard assignments. However, concerning the manning levels, "... just prior to World War II
, [the US] had some 700 people engaged in the effort and [was], in fact, obviously having some successes." Of these, 85% were tasked to decryption and 50% to translation efforts against IJN codes. The nature and degree of these successes has led to great confusion among non-specialists. Furthermore, OP-20-GY "analysts relied as much on summary reports as on the actual intercepted messages."
The U.S. was also given decrypted messages by Dutch (NEI) intelligence, who like the others in the British-Dutch-U.S. agreement to share the cryptographic load, shared information with allies. The U.S. refused to do likewise. This was, at least in part, due to fears of compromise; sharing even between Navy and Army was restricted. The eventual flow of intercepted and decrypted information was tightly and capriciously controlled. At times, even President Roosevelt did not receive all information from code-breaking activities. There were fears of compromise as a result of poor security after a memo dealing with Magic
was tossed in the wastebasket of Brigadier General Edwin M. (Pa) Watson, the President's military aide.
triumph, and proved quite useful later in the War. It was the highest security Japanese Foreign Office system, but prior to Pearl Harbor carried little information about Japanese plans; the military, who were essentially determining foreign policy for Japan, distrusted the Foreign Office and left it "out of the loop". Unfortunately for the U.S., the two U.S. crypto groups generally competed rather than cooperated, and distribution of intelligence from the military to U.S. civilian policy-level officials was poorly done (eg, capriciously selected for distribution) by both the Army and Navy who handled the traffic on alternate days, and furthermore in a way preventing any of its recipients from developing a larger sense of the meaning of the decrypts. Along with the obsession with security, there was little or no analysis done for recipients. Decrypts were typically provided raw, completely without context, and without much taking into account the needs of the recipients. As well, recipients were not permitted to retain them, or notes made from them, again for security reasons.
Most unfortunately, to date not all Purple messages have been released. This was noted as long ago as the Joint Congressional Hearings during the "Magic" testimony. This known fact is often missed, as well as other curious items, for example, the Hearing's questions regarding the missing 25 pages from the Roberts Commission report. Blanket or un-qualified statements on what decoded "Magic" messages revealed are, therefore, premature.
superencrypted code is one of the most debated portions of Pearl Harbor lore. JN-25 is the U.S. Navy's final term for the cryptosystem
the Imperial Japanese Navy
sometimes referred to as Naval Code D. Other names used for it include five-numeral, 5Num, five-digit, five-figure, AN (JN-25 Able), and AN-1 (JN-25 Baker), and so on. It was an example of the then state of the art in crypto systems and was quite different from modern forms of message encryption
in being a code (e.g., battleship = 63982) and further being superenciphered with an additive cypher, taken from a large book. So, for example, 63982 + 12345 = 75227 (using modulo arithmetic, non-carrying addition and non-borrowing subtraction, also called Fibonacci
or "Chinese" addition), giving the actually transmitted group (75227); on receipt the additive was subtracted (75227 - 12345 = 63982 (modulo arithmetic again)) and the code group looked up in the current JN-25 code book. The worth of the additive step is that the next time anyone mentioned 'battleship', a different additive would be used. It was based upon the Japanese syllabary (kana
), due to the difficulties in using kanji
in telegraphy and the fact that teleprinter
s were more or less easily converted (e.g., more characters in the syllabary) to kana from the Roman alphabet.
Superenciphered codes of this sort were widely used and were the state of the art in practical cryptography of the time. JN-25 was very similar in principle to the British "Naval Cypher No. 3", known to have been broken by Germany during World War II.
Once it was realized what sort of cryptosystem JN-25 was, the cryptanalytic approach was known. Stinnett, in fact, notes the existence of a USN handbook for attacks on such a system, produced by OP-20-G. Even so, breaking it was not easy in actual practice. It took much effort and time, not least in accumulating sufficient depth in intercepted messages prior to the outbreak of hostilities when IJN radio traffic increased abruptly and substantially; prior to 7 December 1941, IJN radio traffic was limited, since the IJN played only a minor role in the war against China
and therefore was only rarely required to send radio messages in their highest level crypto system. (As well, interception of IJN traffic off China would have been at best spotty.) Rather oddly however, the official history of GYP-1 shows nearly 45,000 IJN messages intercepted during the period from 1 June 1941 until 4 December 1941. Thus, most Japanese encrypted broadcast military radio traffic was Army traffic associated with the land operations in China.
Breaking a superencrypted cipher like JN-25 was a three-step process: (a) determining the "indicator" method to establish the starting point within the additive cipher, (b) stripping away the superencryption to expose the bare code, and then (c) breaking the code itself. When JN-25 was first detected and recognized, such intercepted messages as were interceptable were collected (at assorted intercept stations around the Pacific by the Navy) in an attempt to accumulate sufficient depth to attempt to strip away the superencryption. Success at doing so was termed by the cryptographers a 'break' into the system. Such a break did not produce a cleartext version of the intercepted message. Only after breaking the underlying code (another difficult process) would the message be available, and even then its meaning—in an intelligence sense—might be less than fully clear.
When a new edition was released, the cryptographers were forced to start again. The original JN-25A system replaced the 'Blue' code (as Americans called it), and used five-digit numbers, each divisible by three (and so usable as a quick, and somewhat reliable, error check, as well as something of a 'crib' to cryptanalysts), giving a total of 33,334 legal code values. To make it harder to crack a code value, meaningless additives (from a large table or book of five-digit numbers) were added arithmetically to each five-digit cipher. JN-25B superseded the first release of JN-25 at the start of December 1940. JN-25B had 55,000 valid words, and while it initially used the same additive list, this was soon changed and the cryptanalysts found themselves entirely blacked out again.
Over the years, various claims have been made as to the progress made decrypting this system, and arguments made over when it was readable (in whole or part). Lt. "Honest John" Leitwiler, Commander of Station CAST
, the Philippines, stated in November 1941 that his staff could “walk right across” the number columns of the coded messages. He is frequently quoted in support of claims JN-25 was then mostly readable. This comment, however, refers not to the message itself but to the superenciphering additives and referred to the ease of attacking the code using a new method for discovery of additive values.
The 16 November 1941 letter to L.W. Parks (OP-20-GY) sent by Leitwiler states, "We have stopped work on the period 1 February to 31 July as we have all we can do to keep up with the current period. We are reading enough current traffic to keep two translators very busy." Another document, Exhibit No. 151 (Memoranda from Captain L. F. Safford) from the Hewitt Inquiry has a copy of the U.S. Navy message OPNAV-242239 'Evaluation of Messages of 26 November 1941' which has in part: '1. Reference (a) advised that Com 16 intercepts were considered most reliable and requested Com 16 to evaluate reports on Japanese naval movements and send dispatch to OPNAV, info CINCPAC. Com 16's estimates were more reliable than Com 14's, not only because of better radio interception, but because Com 16 was currently reading messages in the Japanese Fleet Cryptographic System ("5-number code" or "JN25") and was exchanging technical information and Japanese-to-English translations with the British C. I. Unit at Singapore. Lt. Cdr. Arthur H. McCollum knew this and gave it due consideration when he drafted the McCollum memo
. Duane L. Whitlock, traffic analyst at CAST, was not aware before the attack that IJN movement traffic code was being read. "Reading" in this context means being able to see the underlying code groups, not breaking out the messages into plaintext
. The Hewitt Inquiry document also states, "The "5 numeral system" (JN-25B) yielded no information which would arouse even a suspicion of the Pearl Harbor raid, either before or afterward."
The claim no pre-attack IJN message expressly mentioned Pearl Harbor is perhaps true. Similarly are the claims no Purple traffic likewise pointed to Pearl Harbor. To note, however, in both instances neither all traffic (IJN nor Purple) from these pre-attack intercepts have been declassified and released to the public domain. Hence, any such claims are now indeterminate, pending a fuller accounting.
Additionally, no decrypts have come to light of JN-25B traffic, and importantly identified as such, with any intelligence value prior to Pearl Harbor. Such breaks as recorded by authors W.J. Holmes and Clay Blair, Jr., were into the additive tables, which was a required first step of two. The first 100 JN-25 decrypts from all sources in date/time order of translation have been released, and are available in the National Archives
. The first JN-25B decrypt was in fact by HYPO
(Hawaii) on 8 January 1942 (numbered #1 up JN-25B RG38 CNSG Library, Box 22, 3222/82 NA CP). The first 25 decrypts were very short messages or partial decrypts of marginal intelligence value. As Duane Whitlock stated, "The reason that not one single JN-25 decrypt made prior to Pearl Harbor has ever been found or declassified is not due to any insidious cover-up... it is due quite simply to the fact that no such decrypt ever existed. It simply was not within the realm of our combined cryptologic capability to produce a usable decrypt at that particular juncture."
Detailed month by month progress reports have shown no reason to believe any JN-25B messages were fully decrypted before the start of the war. Tallied results for September, October, and November reveal roughly 3,800 code groups (out of 55,000, about 7%) had been recovered by the time of the attack on Pearl Harbor.
liner , heading from San Francisco to Hawaii on its regular route, is said to have heard and plotted via "relative bearing
s" unusual radio traffic, in a telegraphic code very different from International Morse which persisted for several days, and came from signal source(s) moving in an easterly direction, not shore stations - presumably the approaching Japanese fleet. There are numerous Morse Code
standards including those for Japanese, Korean, Arabic, Hebrew, Russian, and Greek. To the experienced radio operator, each has a unique and identifiable pattern. For example, kana, International Morse, and "Continental" Morse all have a specific rhythmic sound to the "dit" and "dah" combinations. This is how Lurlines radiomen, Leslie Grogan, a U.S. Navy reserve officer in naval communications, and with decades of maritime service in the Pacific identified the mooted signal source as Japanese and not, say, Russian.
There are several problems with this analysis. Surviving officers from the Japanese ships state there was no radio traffic to have been overheard by anyone: their radio operators had been left in Japan to send fake traffic, and all radio transmitters aboard the ships (even those in the airplanes) were physically disabled to prevent any inadvertent or unauthorized broadcast.
The Kido Butai was constantly receiving intelligence and diplomatic updates. Regardless of whether Kido Butai broke radio silence and transmitted, there was a great deal of radio traffic picked up by its antennas. In that time period, it was not unknown for a radio antenna to reflect the energy of an incoming signal back to the ionosphere, where ionospheric skip could result in its reception hundreds or even thousands of miles away. Since the Kido Butai contained a large number of possible reflectors, it thus is conceivable the task force did not break radio silence but was detected anyway.
Such detection would not have helped the Americans track the Japanese fleet. A radio direction finder (DF or RDF) from that time period reported compass direction without reference to distance. (Moreover, it was common for the receiving stations to generate erroneous reciprocal bearings.) To locate the source, a plotter needed two such detections taken from two separate stations to triangulate and find the target. If the target was moving, the detections must be close to one another in time. To plot the task force's course with certainty, at least four such detections must have been made in proper time-pairs, and the information analyzed in light of further information received by other means. This complex set of requirements did not occur; if the Kido Butai was detected, it was not tracked.
According to a 1942 Japanese after action report
, "In order to keep strict radio silence, steps such as taking off fuses in the circuit, and holding and sealing the keys were taken. During the operation, the strict radio silence was perfectly carried out... The Kido Butai used the radio instruments for the first time on the day of the attack since they had been fixed at the base approximately twenty days before and proved they worked well. Paper flaps had been inserted between key points of some transmitters on board to keep the strictest radio silence..." Commander Genda
, who helped plan the attack, stated, "We kept absolute Radio Silence." For two weeks before the attack, the ships of Kido Butai used flag and light signals (semaphore
and blinker), which were sufficient since task force members remained in line of sight. Kazuiyoshi Koichi, the Communications Officer for , dismantled vital transmitter parts and kept them in a box that he used as a pillow to prevent Hiei from making any radio transmissions until the attack commenced. Lieutenant Commander Chuichi Yoshoka, communications officer of the flagship, Akagi, said he did not recall any ship sending a radio message before the attack. Furthermore, Captain Kijiro, in charge of the Kido Butais three screening submarines, stated nothing of interest happened on the way to Hawaii. Vice Admiral Ryūnosuke Kusaka stated, "It is needless to say that the strictest radio silence was ordered to be maintained in every ship of the Task Force. To keep radio silence was easy to say, but not so easy to maintain." There is nothing in the Japanese logs or after action report indicating that radio silence was broken until after the attack. Kusaka worried about this when it was briefly broken on the way home.
The appendix to the war-initiating operational order is also often debated. The message of 25 November 1941 from CinC Combined Fleet (Yamamoto) to All Flagships stated, "Ships of the Combined Fleet will observe radio communications procedure as follows: 1. Except in extreme emergency the Main Force and its attached force will cease communicating. 2. Other forces are at the discretion of their respective commanders. 3. Supply ships, repair ships, hospital ships, etc., will report directly to parties concerned." Furthermore, "In accordance with this Imperial Operational Order, the CinC of the Combined Fleet issued his operational order ... The Task Force then drew up its own operational order, which was given for the first time to the whole force at Hitokappu Bay... In paragraph four of the appendix to that document, the especially secret Strike Force was specifically directed to 'maintain strict radio silence from the time of their departure from the Inland Sea. Their communications will be handled entirely on the general broadcast communications net.'" In addition, Genda recalled, in a 1947 interview, Kido Butais communications officer issuing this order, with the task force to rely (as might be expected) on flag and blinker.
The original records of Lurline surrendered to Lt. Cmdr. George W. Pease, 14th Naval District in Honolulu, have disappeared. Neither Lurlines log, nor the reports to the Navy or Coast Guard by Grogan in Hawaii can be found. Thus no contemporaneously written evidence of what was recorded aboard Lurline is now available. Grogan commented on a signal source "moving" eastward in the North Pacific over several days as shown via "relative bearings" which then "bunched up" and stopped moving. However, the directions given by Grogan in a recreation of the logbook for the Matson Line were 18 and 44° off from known strike force positions and instead pointed towards Japan. According to author Jacobsen, Japanese commercial shipping vessels are the likely source. A recently discovered missing report by Grogan, dated 10 December 1941 and titled "Record for Posterity", also does not support claims of Kido Butai broadcasting.
The Japanese practiced radio deception
. Susumu Ishiguru, intelligence and communications officer for Carrier Division Two, stated, "Every day false communications emanated from Kyushu at the same time and same wavelength as during the training period." Because of this, Commander Joseph Rochefort
of Hawaii Signals Intelligence
concluded that the First Air Fleet remained in home waters for routine training. The ships left their own regular wireless operators to carry on "routine" radio traffic. Captain Sadatoshi Tomioka stated, "The main force in the Inland Sea and the land-based air units carried out deceptive communications to indicate the carriers were training in the Kyushu area." The main Japanese naval bases (Yokosuka, Kure, and Sasebo) all engaged in considerable radio deception. Analysis of the bearings from Navy DF stations account for claimed breaks of radio silence, and when plotted, the bearings point to the Japanese naval bases, not where those ships actually were.
Rochefort, with Huckins and Williams, states there were no dummy messages used at any time throughout 1941 and no effort by the Japanese to use serious deception. When asked after the attack just how he knew where Akagi was, Rochefort (who commanded HYPO at the time) said he recognized her "same ham-fisted" radio operators. (The Japanese contend that radio operators were left behind as part of the deception operation.) The critical DF-tracked radio transmissions show bearings that could have not come from the strike force. Emissions monitored from CAST, or CAST's report Akagi was off Okinawa on 8 December 1941, are examples, though some transmissions continue to be debated. The contention that "low-powered" radio (such as VHF
or what the U.S. Navy called TBS, or talk between ships), might have been used, and detected, is contradicted as impossible due to the tremendous distances involved and when contact was lost, it was routinely presumed it was because low-powered radio and land line were being used. Freedom of Information Act (FOIA) requests for specific RDF reports remain wanting. "A more critical analysis of the source documentation shows that not one single radio direction finder bearing, much less any locating "fix," was obtained on any Kido Butai unit or command during its transit from Saeki Bay, Kyushu to Hitokappu Bay and thence on to Hawaii. By removing this fallacious lynchpin propping up such claims of Kido Butai radio transmissions, the attendant suspected conspiracy tumbles down like a house of cards."
One suggested example of a Kido Butai transmission is the November 30, 1941 COMSUM14 report in which Rochefort mentioned a "tactical" circuit heard calling "marus"
. (a term often used for commercial vessels or non-combat units). Further, the perspective of U.S. naval intelligence at the time was, "... The significance of the term, 'tactical circuit' is that the vessel itself, that is Akagi, was using its own radio to call up the other vessels directly rather than work them through shore stations via the broadcast method which was the common practice in Japanese communications. The working of the Akagi with the Marus, indicated that she was making arrangements for fuel or some administrative function, since a carrier would rarely address a maru."
Also, from a U.S. Navy radiomen on duty at STATION AE (STATION Able Easy, Sitka, Alaska) at the time of Pearl Harbor, Elmer H. Frantz, states, "It is inconceivable to me that a force represented by the Kido Butai with 33 ships involved of all different types ... and no radio communications, communication black out on orders - I just don't believe it."
One story from author Constantine Fitzgibbon claimed that a letter received from V. F. W. Cavendish-Bentinck stated Britain's JIC met and discussed at length the impending Japanese attack on Pearl Harbor. From a Joint Intelligence Sub-Committee session of 5 December 1941 it was stated "We knew that they changed course. I remember presiding over a J.I.C. meeting and being told that a Japanese fleet was sailing in the direction of Hawaii, asking 'Have we informed our transatlantic brethren?' and receiving an affirmative reply." However the author was incorrect. There was no session on the 5th of Dec nor was Pearl Harbor discussed when they did meet on the 3rd.
Frank E. Beatty
, who at the time of the Pearl Harbor attack was an aide to the Secretary of the Navy
Frank Knox
and was very close to President Franklin D. Roosevelt
's inner circle
, with perspicuous remarks as:
Another "eye witness viewpoint" akin to Beatty's is provided by Roosevelt's administrative assistant at the time of Pearl Harbor, Jonathan Daniels; it is the telling comment about FDR's reaction to the attack - "The blow was heavier than he had hoped it would necessarily be. ... But the risks paid off; even the loss was worth the price. ..."
"Ten days before the attack on Pearl Harbor
", Henry L. Stimson
, United States Secretary of War
at the time "entered in his diary the famous and much-argued statement - that he had met with President Roosevelt to discuss the evidence of impending hostilities with Japan, and the question was 'how we should maneuver them [the Japanese] into the position of firing the first shot without allowing too much danger to ourselves.'" However Stimson, in reviewing his diary after the war, recalled that the commanders at Pearl Harbor had been warned of the possibility of attack, and that the poor state of readiness that the attack had revealed was a surprise to him:
Stimson omits to mention the "war warning" message expressly told Short not to alarm the civilian population and to be alert for sabotage, which was widely expected to be a precursor to attack.
Robert Stinnett's Day of Deceit suggests a memorandum
prepared by Commander McCollum was central to U.S. policy in the immediate pre-war period. Stinnett claims the memo suggests only a direct attack on U.S. interests would sway the American public (or Congress) to favor direct involvement in the European war, specifically in support of the British. An attack by Japan would not, could not, aid Britain, as history would prove. Although the memo was passed to Captains Walter Anderson and Dudley Knox, two of Roosevelt's military advisors, on October 7, 1940, there is no evidence to suggest Roosevelt ever saw it, while Stinnett's claims of evidence he did is nonexistent. Moreover, although Anderson and Knox offered eight specific plans to aggrieve the Japanese Empire and added, "If by these means Japan could be led to commit an overt act of war, so much the better," of the eight "plans" (actions to be taken) offered in the memo, only one was ever implemented in any fashion, and there is considerable doubt the memo was the inspiration. Nonetheless, in Day of Deceit Stinnett claims all action items were implemented. Yet there were numerous instances of members of the Roosevelt Administration insisting on not provoking Japan. Mark Parillo, in his essay The United States in the Pacific, wrote, "[t]hese theories tend to founder on the logic of the situation. Had Roosevelt and other members of his administration known of the attack in advance, they would have been foolish to sacrifice one of the major instruments needed to win the war just to get the United States into it." Furthermore, on 5 November 1941, in a joint memo, Stark
, CNO
, and Marshall
, Army Chief of Staff, warned, "if Japan be defeated and Germany remain undefeated, decision will still not have been reached.... War between the United States and Japan should be avoided...." Additionally, in a 21 November 1941 memo, Brigadier Leonard T. Gerow
, head of Army War Plans, stated, "one of our present major objectives [is] the avoidance of war with Japan...[and to] insure continuance of material assistance to the British." He concluded, "[I]t is of grave importance to our war effort in Europe..." Furthermore, Churchill himself, in a 15 May 1940 telegram, said he hoped a U.S. commitment to aid Britain would "quiet" Japan, following with a 4 October message requesting a USN courtesy visit to Singapore aimed at "preventing the spreading of the war" And Stark's own Plan Dog
expressly stated, "Any strength that we might send to the Far East would...reduce the force of our blows against Germany..." Roosevelt could scarcely have been ignorant of Stark's views, and war with Japan was clearly contrary to Roosevelt's express wish to aid Britain and with Churchill's to "quiet" Japan.
One quote is often used to add legitimacy to the notion the British Government knew in advance the attack was coming. Oliver Lyttelton, the British Minister of War Production, said, "...Japan was provoked into attacking the Americans at Pearl Harbor. It is a travesty of history ever to say that America was forced into the war. Everyone knows where American sympathies were. It is incorrect to say that America was truly neutral even before America came into the war on an all-out basis." How this demonstrates anything with regard to Japan is unclear. Rather, it refers to other aid to Britain. Lend-Lease
, enacted in March 1941, informally declared the end of American neutrality in favor of the Allies by agreeing to supply Allied nations with war materials. In addition, Roosevelt authorized a so-called Neutrality Patrol
, which would protect the merchantmen of one hostile nation, Britain, from attack by another, Germany. This made shipping legitimate target of attack by submarine. Furthermore, Roosevelt ordered U.S. destroyer
s to report U-boat
s, then later authorized them to "shoot on sight". This made the U.S. a de facto belligerent. None was the act of a disinterested neutral, while all are unquestionably of assistance to Britain.
When considering information like this as a point for or against, the reader must keep in mind questions such as: was this official privy to information about the U.S. government? Did he have communications with high-level administration figures such as President Roosevelt or Ambassador Joseph Grew
? Is this just a strongly held personal opinion? Or were there measures justifying this view? If Britain, did, indeed know and chose to conceal, "withholding this vital intelligence only ran the risk of losing American trust", and with it any further American aid, which would be reduced after the attack in any event.
There is also a claim, first asserted in Toland's Infamy, ONI knew about Japanese carrier movements. Toland cited entries from the diary of Rear Admiral J. E. Meijer Ranneft of the Dutch Navy for 2 December and 6 December. Ranneft attended briefings at ONI on these dates. According to Toland, Ranneft wrote that he was told by ONI that two Japanese carriers were northwest of Honolulu. However, the diary uses the Dutch abbreviation beW, meaning "westerly", contradicting Toland's claim. Nor did any other persons present at the briefings report hearing Toland's version. In their reviews of Infamy, David Kahn and John C. Zimmerman suggested Ranneft's reference was to carriers near the Marshall Islands. Toland has made other conflicting and incorrect claims about the diary during lectures at the Holocaust denial organization the Institute for Historical Review
.
The diary states at 02:00 (6-12-41) Turner fears a sudden Japanese attack on Manila. At 14:00 the diary states "Everyone present on O.N.I. I speak to Director Admiral Wilkinson, Captain MacCollum, Lt. Cdr. Kramer...They show me – on my request – the place of the 2 carriers (see 2–12–41) West of Honolulu. I ask what the idea is of these carriers on that place. The answer was: 'perhaps in connection with Japanese rapports [sic] on eventual American actions'. There is not one of ours who speaks about a possible air attack on Honolulu. I myself did not think of it because I believed everyone on Honolulu to be 100% on the alert, as everyone here on O.N.I. There prevails a tense state of mind at O.N.I." These diary entries are provided (in Dutch) in the photo section in George Victor's The Pearl Harbor Myth: Rethinking the Unthinkable.
On October 7, 1940, Lieutenant Commander
Arthur H. McCollum of the Office of Naval Intelligence
submitted a memo to Navy Captains Walter S. Anderson and Dudley Knox, which details eight actions which might have the effect of provoking Japan into attacking the United States. The memo remained classified
until 1994.
Sections 9 and 10 of the memo are cited as the "smoking gun", and a primary thesis of Stinnett's book, suggesting it was central to the high level conspiracy
to lure the Japanese into an attack. Evidence the memo or derivative works actually reached President Roosevelt, senior administration officials, or the highest levels of U.S. Navy command, is largely conjectural.
In actuality, Stinnett attributes to McCollum a position McCollum expressly refuted. Furthermore, McCollum's own sworn testimony also refutes it.
agents. One of them, Otto Kuhn, was a sleeper agent
living in Hawaii with his family. Kuhn was incompetent and there is no evidence he provided information of value. The other, Yugoslavia
n businessman Dusko Popov, was a double agent, working for the XX Committee of MI5
. In August 1941, he was sent by the Abwehr to the U.S., with an assignment list that included specific questions about military facilities in Oahu, including Pearl Harbor. The FBI seems to have paid little attention. J. Edgar Hoover
dismissed Popov as unimportant, and there is nothing to show his assignment list was passed on to military intelligence, nor was he allowed to visit Hawaii. Popov later asserted his list was a clear warning of the attack, ignored by the bungling FBI. The questions in his list were rambling and general, and in no way pointed to air attack on Pearl Harbor, & Prange considered Popov's claim overblown, and argued the notorious questionnaire was a product of Abwehr thoroughness.
Another intended agent was the highly decorated former RAF Squadron-
Leader Frederick Joseph Rutland who helped the Japanese navy develop aircraft
carriers in the 1920s, and in the 1930s was deployed as a secret agent in the
USA. But for problems with establishing his cover in Hawaii as a whisky
importer, Rutland would have been the key Japanese naval intelligence spy
supporting the attack on Pearl Harbor in December 1941.
Furthermore, the Japanese did not need Abwehr assistance, having a consulate in Hawaii which had on its staff an undercover IJN intelligence officer, Takeo Yoshikawa
. The consulate had reported to IJN Intelligence for years, and Yoshikawa increased the rate of reports after his arrival. (Sometimes called a "master spy", he was in fact quite young, and his reports not infrequently contained errors.) Pearl Harbor base security was so lax Yoshikawa had no difficulty obtaining access, even taking the Navy's own harbor tourboat. (Even had he not, hills overlooking the Harbor were perfect for observation or photography, and were freely accessible.) Gossip with taxi drivers is supposed to have been one of his sources as well. Some of his information, and presumably other material from the Consulate, was hand-delivered to IJN intelligence officers aboard Japanese commercial vessels calling at Hawaii prior to the War; at least one is known to have been deliberately routed to Hawaii for this purpose during the summer. Most, however, seem to have been transmitted to Tokyo, almost certainly via cable (the usual communication method with Tokyo). Many of those messages were intercepted and decrypted by the U.S.; most were evaluated as routine intelligence gathering all nations do about potential opponents, rather than evidence of an active attack plan. None of those currently known, including those decrypted after the attack when there was finally time to return to those remaining undecrypted, explicitly stated anything about an attack on Pearl Harbor. The only exception was a message sent from the Hawaiian Consulate on 6 December, which was not decrypted until after the 7th, making it moot with respect to U.S. foreknowledge. No cable traffic was intercepted in Hawaii until after David Sarnoff
of RCA
agreed to assist during a visit to Hawaii immediately before the 7th. Such interception was illegal under U.S. law, though it had been going on sub rosa
in New York for some time. Farago's postscript offers a viewpoint from RCA personnel. In the final analysis, illegal co-operation of American cable companies changed little or nothing, since radio intercept stations were picking up some of the consular traffic anyway, and American intelligence failed to make optimum use of the information in any case.
Throughout 1941, the U.S., Britain, and the Netherlands collected considerable evidence suggesting Japan was planning some new military adventure. The Japanese attack on the U.S. in December was essentially a side operation to the main Japanese thrust to the South against Malaya
and the Philippines
—many more resources, especially Imperial Army resources, were devoted to these attacks as compared to Pearl Harbor. Many in the Japanese military (both Army and Navy) had disagreed with Admiral Isoroku Yamamoto
's idea of attacking the U.S. Fleet at Pearl Harbor when it was first proposed in early 1941, and remained reluctant after the Navy approved planning and training for an attack beginning in spring 1941, and through the highest level Imperial Conferences in September and November which first approved it as policy (allocation of resources, preparation for execution), and then authorized the attack. The Japanese focus on South-East Asia was quite accurately reflected in U.S. intelligence assessments; there were warnings of attacks against Thailand
(the Kra Peninsula), Malaya, French Indochina
, the Dutch East Indies
(Davao-Weigo Line), the Philippines, even Russia
. Pearl Harbor was not mentioned. In fact, when the final part of the "14-Part Message" (also called the "one o'clock message") crossed Kramer's desk, he cross-referenced the time (per usual practice, not the brainwave often portrayed) and tried to connect the timing to a Japanese convoy (the Thai invasion force) recently detected by Admiral Hart
in the Philippines.
The U.S. Navy was aware of the traditional planning of the Imperial Japanese Navy for war with the U.S., as maintained throughout the 1930s and into the 1940s. The Japanese made no secret of it, and in the 1930s American radio intelligence gave U.S. war planners considerable insight in Japanese naval exercises. These plans presumed there would be a large decisive battle between Japanese and U.S. battleships, but this would be fought near Japan, after the numerical superiority of the U.S. Pacific Fleet (assured by the Washington Naval Treaty
, and still taken as given) was whittled down by primarily night attacks by light forces, such as destroyers and submarines. This strategy expected the Japanese fleet to take a defensive posture, awaiting U.S. attack, and it was confirmed by the Japanese Navy staff only three weeks before Pearl Harbor. In the 1920s, the decisive battle was supposed to happen near the Ryukyu islands; in 1940 it was expected to occur in the central Pacific, near the Marshall islands. War Plan Orange
reflected this in its own planning for an advance across the Pacific. Yamamoto's decision to shift the focus of the confrontation with the U.S. as far east as Pearl Harbor, and to use his aircraft carriers to cripple the American battleships, was a radical enough departure from previous doctrine to leave analysts in the dark.
There had been a specific claim of a plan for an attack on Pearl Harbor from the Peru
vian Ambassador to Japan in early 1941. (The source of this intelligence was traced to the Ambassador's Chinese cook. It was treated with skepticism, and properly so, given the nascent state of planning for the attack at the time and the unreliability of the source.) Since Yamamoto had not yet decided to even argue for an attack on Pearl Harbor, discounting Ambassador Grew's report to Washington in early 1941 was quite sensible. Later reports from a Korean labor organization also seem to have been regarded as unlikely, though they may have had better grounding in actual IJN actions. There has been uncovered no record of a serious belief or conviction by anyone in U.S. or UK military intelligence (in Hawaii, DC or elsewhere), or among U.S. civilian policy officials, prior to the attack, of Pearl Harbor or the U.S. West Coast as a potential target.
" announcing the direction of new hostilities via a broadcast weather 'forecast', remains a curious and confusing episode, demonstrating the uncertain meaning inherent in most raw intelligence information, and its handling/mis-handling - and in this case, even uncertainty about the existence of some intelligence information, or of its active removal from official records, especially some years after the event.
At most, however, the Winds system was to be implemented only if the communications between Japan and Washington were cut, and since this never obtained prior to the attack, there was no need for it. Given this, any talk of intercepted "Winds" messages would appear to be specious. Note, however, in Safford's testimony on this topic he states very clearly London (not Washington) was the addressee of this message.
There are two problems with this evaluation. First, there is Admiral King's endorsement of the Navy Court of Inquiry, page 344, reading in part, " ... (3) Admiral Kimmel was not informed of the implementation of the "Winds Message". Admiral Stark says he never got this information himself, but it is clear that it did reach Admiral Stark's office. This, together with the handling of other matters of information, indicates some lack of efficiency in Admiral Stark's organization. ..." Second, there exists more documentation for the "Winds Execute" which relates an account of interception of the "Winds Execute", passing the message to ONI, and later, his direct order from Captain Harper not to testify in support of Safford at one of the Pearl Harbor hearings. Also see RG457 SRH-255 Archives II College Park MD where Ogg's statements during an interview by Captain Irwin G. Newman were considerably different from Toland's attributions and amplified by authors Stinnett and Wilford, and where neither Ogg or Newman ever mention the Winds code topic.
and General Walter C. Short
. Washington did not solicit their views about likelihood of war or Hawaiian special concerns. Washington's war warning messages have also been criticised by some (e.g., the U.S. Army Pearl Harbor Board - "Do/Don't Messages") as containing "conflicting and imprecise" language.
Since the Army was officially responsible for the security of the Pearl Harbor facilities and Hawaiian defense generally, and so of the Navy's ships while in port, Army actions are of particular interest. Short reported to Washington he had increased his alert level (but his earlier change in meaning for those levels was not understood in Washington and led to misunderstanding there about what he was really doing). In addition, Short's main concern was sabotage from fifth columnists (expected to precede the outbreak of war for decades preceding the attack), which accounts for his orders that Army Air Corps planes be parked close together near the center of the airfields. There seems to have been no increased Army urgency about getting its existing radar equipment properly integrated with the local command and control in the year it had been available and operational in Hawaii before the attack. Leisurely radar training continued and the recently organized early warning center was left minimally staffed. Anti-aircraft guns remained in a state of low readiness, with ammunition in secured lockers. Neither Army long range bombers nor Navy PBYs were used effectively, remaining on a peacetime maintenance and use schedule. Short evidently failed to understand he had the responsibility to defend the fleet. In Short's defense, it should be noted he had training responsibilities to meet, and the best patrol aircraft, B-17s and B-24s, were in demand in the Philippines and Britain, both of which had higher priority.
Little was done to prepare for air attack. Inter-service rivalries
between Kimmel and Short did not improve the situation. Particularly, most intelligence information was sent to Kimmel, assuming he would relay it to Short, and vice versa; this assumption was honored mostly in the breach. Hawaii did not have a Purple cipher machine (although, by agreement at the highest levels between U.S. and UK cryptographic establishments, four had been delivered to the British by October 1941), so Hawaii remained dependent on Washington for intelligence from that (militarily limited) source. However, since Short had no liaison with Kimmel's intelligence staff, he was usually left out of the loop. Henry Clausen
reported the war warnings could not be more precise because Washington could not risk Japan guessing the U.S. was reading important parts of their traffic (i.e., most importantly Purple, despite the fact there was no known tactical or strategic info in that traffic), as well as the fact neither was cleared to receive Purple; Clausen does not answer why Washington could not have said "an exceptionally reliable source" was involved, with very strong instructions to pay attention.
Additionally, Clausen claims military men of Kimmel and Short's seniority and background should have understood the significance of the warnings, and should have been more vigilant than they were, as for instance in scouting plane flights from Hawaii, which were partial at best in the period just before the attack. All other Pacific commands took appropriate measures for their situations.
Like most commentators, Clausen ignores what the "war warnings" (and their context) explicitly warn, though indistinctly, against. Washington, with more complete intelligence than any field command, expected an attack anywhere on a list of possible locations (Pearl Harbor not among them), and since the Japanese were already committed to Thailand, it seems to have been expected another major operation by them was impossible. Clausen, like most, also ignores what actions Kimmel, Short, and Admiral Claude C. Bloch
(Commander, Fourteenth Naval District, responsible for naval facilities in Hawaii) actually took. They took precautions against sabotage, widely expected as a precursor to war, and reported their preparations. The Hawaii commanders did not anticipate an air attack; no one did so explicitly. Indeed, the prevailing view at the time was Japan could not execute two major naval operations at once, so with the Thailand invasion convoy known to be at sea, the Hawaii commanders had good reason to feel safe.
One major point often omitted from the debate (though Costello covers it thoroughly) is the Philippines, where MacArthur, unlike Kimmel or Short, had complete access to all decrypted Purple and JN-25 traffic CAST could provide (indeed, Stinnet quotes Whitlock to that effect), and was nonetheless caught unprepared and with all planes on the ground nevertheless, nine hours after the Pearl Harbor attack. Caidin and Blair also raise the issue.
Although it has been argued that there was sufficient intelligence at the time to give commanders at Pearl Harbor a greater level of alert, some factors may take on unambiguous meaning not clear at the time, lost in what Roberta Wohlstetter in her masterful examination of the situation called "noise", "scattered amid the dross of many thousands of other intelligence bits, some of which just as convincingly pointed to a Japanese attack on the Panama Canal."
Not all in the U.S. Navy shared this opinion. A mock air attack on Pearl Harbor during war games in the 1930s was judged to have been a success. Shortly after taking office, Navy Secretary Knox wrote an overview memo which specifically noted the possibility of an attack at Pearl Harbor. However, neither observation led to formal policy recommendations to forestall such an attack. Admiral James O. Richardson, who was fired by President Roosevelt for refusing to station the Pacific Fleet in Pearl Harbor, blamed the President for the "initial defeats in the Pacific" as "direct, real and personal." Richardson believed stationing the fleet in Pearl Harbor made the ships extremely vulnerable against attack and provided a poor and unstrategic defense.
The British proved torpedoes, modified for shallow water, could be effective in their attack on the Regia Marina
at Taranto
on November 11, 1940. The U.S. Navy discussed this new development as can be seen in a June 1941 memo, as Taranto was about 75 ft (22.9 m) deep and Pearl less than 40 ft (12.2 m). The British attack method was not considered relevant to a torpedo attack at Pearl.
The Royal Navy
had used Swordfish
torpedo planes, and their low speed was part of the reason the Taranto attack succeeded. The Imperial Japanese Navy
no longer had any similar planes, so they had to develop other methods, both hardware and delivery technique. They independently developed shallow water torpedo modifications (called "Thunder Fish") during the planning and training for the attack in 1941. Wooden fins were added to the tail and anti-roll "flippers" kept the torpedo upright once in the water. The fins kept the torpedo's nose level in the air and broke off on entering the water. The flatter "flight" trajectory helped keep them from diving so deeply as to encounter bottom mud. (Despite these modifications, some Japanese torpedoes did indeed reach the bottom and several remain unaccounted for.) These simple modifications were not anticipated by the USN, and Admiral Bloch (commander of the Pearl Harbor Naval District) did not push to install torpedo nets
or baffles at Pearl. Nor, it seems, did anyone else. Practical considerations also were an influence. Due to the shallow anchorage (which continues to require regular dredging), installation of torpedo nets would have severely restricted the mobility of vessels in the harbor.
Kimmel and his staff testified regarding torpedo nets and booms: "(m) Fact XV ... The decision not to install baffles appears to have been made by the Navy Department." That is, in Washington, DC, rather than in Hawaii.
In fact, the two carriers then operating with the Pacific Fleet, Enterprise and Lexington, were on missions to deliver fighters to Wake and Midway Islands, which were intended in part to protect the route used by planes (including B-17s) bound for the Philippines. (The third, Saratoga, was in routine refit
in Puget Sound
, at the Bremerton shipyard.) At the time of the attack, Enterprise was about 200 mi (173.8 nmi; 321.9 km) west of Pearl Harbor, heading back. In fact, Enterprise had been scheduled to be back on December 6, but was delayed by weather. A new arrival estimate put her arrival at Pearl around 07:00, almost an hour before the attack, but she was also unable to make this schedule.
Furthermore, at the time, aircraft carriers were classified as fleet scouting elements, and hence relatively expendable. They were not capital ship
s. The most important vessels in naval planning even as late as Pearl Harbor were battleships (per the Mahan doctrine
followed by both the U.S. and Japanese navies at the time). Carriers became the Navy's most important ships only following the attack.
At the time, naval establishments all over the world regarded battleships, not carriers, as the most powerful and significant elements of naval power. Had the U.S. wanted to preserve its key assets from attack, it would almost certainly have focused on protecting battleships. It was the attack on Pearl Harbor itself that first helped vault the carrier ahead of the battleship in importance. The attack demonstated the carrier's unprecedented ability to attack the enemy at a great distance, with great force and surprise. The U.S. would turn this ability against Japan. Elimination of battleships from the Pacific Fleet forced the Americans to rely on carriers for offensive operations. To posit the preservation of the carriers as proof or evidence of advance knowledge of the attack is untenable.
McDonald called back the Opana radar when he reached Pvt. Joseph Lockard. Lockard told McDonald that the radar return was the largest that he had ever seen. McDonald insisted that Tyler speak directly to Lockard. Lockard was told "Well don't worry about it." McDonald asked Tyler if he should call back the plotters and warn Wheeler Field. Tyler indicated that it was not necessary.
The initial radar returns were thought by the ill-trained junior officer to be a flight of American bombers expected from the mainland. In fact those bombers did arrive, from a somewhat different bearing in the middle of the attack. Additionally, Japanese submarines were sighted and attacked (by the destroyer ) outside the harbor entrance a few hours before the attack commenced, and at least one was sunk—all before the planes came within even radar range. This might have provided enough notice to disperse aircraft and fly off reconnaissance, except, yet again, reactions of the duty officers were tardy. It has been argued that failure to follow up on DF bearings saved . If she had been correctly directed, she might have run into the six carrier Japanese strike force.
After the attack, the search for the attack force was concentrated south of Pearl Harbor, continuing the confusion and ineffectiveness of the American response.
Theorists challenging the traditional view that Pearl Harbor was a surprise, repeatedly note that Roosevelt wanted (though did not say so officially) the U.S. to intervene in the war against Germany. A basic understanding of the political situation of 1941 precludes such an understanding as reasonable evidence Roosevelt invited, allowed, or even knew of the Pearl Harbor attack. Military historian and novelist Thomas Fleming, argues that President Roosevelt, himself, had wished for Germany or Japan to strike the first blow, but did not expect the United States to be hit as severely as she was in the attack on Pearl Harbor.
An attack by Japan on the U.S. could not guarantee the U.S. would declare war on Germany. After such an attack, American public anger would be directed at Japan, not Germany, just as happened. The Tripartite Pact (Germany, Italy, Japan) called for each to aid another in defense; Japan could not reasonably claim America had attacked Japan if she struck first. For instance, Germany had been at war with the UK since 1939, and with the USSR since June 1941, without Japanese assistance. There had been a serious, if low-level, naval war going on in the Atlantic between Germany and the U.S. since summer of 1941, as well. Nevertheless, it was only Hitler's declaration of war on 11 December, unforced by treaty, that brought the U.S. into the European war.
Clausen and Lee's Pearl Harbor: Final Judgement contains some interesting information on the intelligence available to Roosevelt and Churchill prior to the attack. On page 367 in the Appendix is a Purple message, dated 29 November 1941, from the Japanese Ambassador in Berlin to Tokyo. A closing paragraph reads, "... He (Ribbentrop) also said that if Japan were to go to war with America, Germany would, of course, join in immediately, and Hitler's intention was that there should be absolutely no question of Germany making a separate peace with England. ..." According to David Irving
, Churchill (having full access to Purple traffic) was well aware of this message, noting it in red ink. While theorists challenging the conventional view the attack was a surprise treat this as a guarantee to join after Japan's attack, it can as easily be taken as a guarantee to come to Japan's aid, as Germany had done for Italy in Libya
.
For instance, Sheet No. 94644 derives from its reference in the FOIA-released Japanese Navy Movement Reports of Station H in November 1941. Entries for 28 November 1941 have several more items of interest, each being a "movement code" message (indicating ship movements or movement orders), with specific details given by associated Sheet Numbers. Examples are: Sheet No. 94069 has information on "KASUGA MARU" - this being hand-written (Kasuga Maru was later converted to CVE Taiyo
); Sheet No. 94630 is associated with IJN oiler Shiriya (detailed to the Midway Neutralization Force, with destroyers Ushio and Sazanami, not the Kido Butai); and finally for Sheet No. 94644 there is another hand-written remark "FAF using Akagi xtmr" (First Air Fleet using Akagis transmitter). It is known the movement reports were largely readable at the time.
These three documents (Sheet Numbers 94069, 94630, and 94644) are examples of materials which yet, even after decades and numerous specific FOIA requests, have not been declassified fully and made available to the public. Sheet Number 94644, for example, noted as coming from Akagis transmitter and as being a "movement code" report, would have likely contained a reported position.
Another issue in the debate is the fact neither Admiral Kimmel nor General Short ever faced court martial. It is alleged this was to avoid disclosing information showing the U.S. had advanced knowledge of the attack. When asked, "Will historians know more later?", Kimmel replied, "' ... I'll tell you what I believe. I think that most of the incriminating records have been destroyed. ... I doubt if the truth will ever emerge.' ..." From Vice Admiral Libby, "I will go to my grave convinced that FDR ordered Pearl Harbor to let happen.
He must have known." It is equally likely this was done to avoid disclosing the fact Japanese codes were being read, given there was a war on.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
officials had advance knowledge of Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
's December 7, 1941 attack on Pearl Harbor
Attack on Pearl Harbor
The attack on Pearl Harbor was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941...
. Ever since the Japanese attack there has been debate as to how and why the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
had been caught off guard and how much and when American officials knew of Japanese plans for an attack.
Several writers, including journalist Robert Stinnett
Robert Stinnett
Robert B. Stinnett is a former American sailor who earned ten battle stars and a Presidential Unit Citation. He is the author of Day of Deceit, regarding U.S. government advance knowledge of the World War II Pearl Harbor attack.-Biography:...
and former United States Navy Rear Admiral Robert A. Theobald
Robert Alfred Theobald
Robert Alfred Theobald , nicknamed "Fuzzy", was a United States rear admiral who served in World War I and World War II, and was the author of the 1954 book The Final Secret of Pearl Harbor: The Washington Background of the Pearl Harbor Attack.-Biography:Born in San Francisco, California, Theobald...
, have argued that various parties high in the U.S. and British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
governments knew of the attack in advance and may even have let it happen or encouraged it in order to force America into war via the "back door." Evidence supporting this view is taken from quotations and source documents from the time and the release of newer materials.
Ten official U.S. inquiries
The U.S. government made nine official inquiries into the attack between 1941 and 1946, and a tenth in 1995. They included an inquiry by Secretary of the NavyUnited States Secretary of the Navy
The Secretary of the Navy of the United States of America is the head of the Department of the Navy, a component organization of the Department of Defense...
Frank Knox
Frank Knox
-External links:...
(1941); the Roberts Commission
Roberts Commission
Two presidentially-appointed commissions have been described as "the Roberts Commission." One related to the circumstances of the Japanese attack on Pearl Harbor, and another related to the protection of cultural resources during and following World War II...
(1941–42); the Hart Inquiry (1944); the Army Pearl Harbor Board (1944); the Naval Court of Inquiry (1944); the Hewitt investigation; the Clarke investigation; the Congressional Inquiry (1945–46); a top-secret inquiry by Secretary of War
United States Secretary of War
The Secretary of War was a member of the United States President's Cabinet, beginning with George Washington's administration. A similar position, called either "Secretary at War" or "Secretary of War," was appointed to serve the Congress of the Confederation under the Articles of Confederation...
Henry L. Stimson
Henry L. Stimson
Henry Lewis Stimson was an American statesman, lawyer and Republican Party politician and spokesman on foreign policy. He twice served as Secretary of War 1911–1913 under Republican William Howard Taft and 1940–1945, under Democrat Franklin D. Roosevelt. In the latter role he was a leading hawk...
, authorized by Congress and carried out by Henry Clausen
Henry Clausen
Henry Christian Clausen was the author of the Clausen Report, an 800-page report on the Army Board’s Pearl Harbor Investigation. He traveled over 55,000 miles over seven months in 1945, and interviewed nearly a hundred personnel, Army, Navy, British and civilian, as a Special Investigator for the...
(the Clausen Inquiry; 1946); and the Thurmond-Spence hearing, in April 1995, which produced the Dorn Report. The inquiries reported incompetence, underestimation, and misapprehension of Japanese capabilities and intentions; problems resulting from excessive secrecy about cryptography
Cryptography
Cryptography is the practice and study of techniques for secure communication in the presence of third parties...
; division of responsibility between Army and Navy (and lack of consultation between them); and lack of adequate manpower for intelligence (analysis, collection, processing).
Investigators prior to Clausen did not have the security clearance necessary to receive the most sensitive information,. Clausen claimed that, in spite of Secretary Stimson having given him a letter informing witnesses that he had the necessary clearances to require their cooperation, he was repeatedly lied to until he produced copies of top secret decrypts, thus proving he indeed had the proper clearance.
Stimson's report to Congress, based on Clausen's work, was limited due to secrecy concerns, largely about cryptography. A more complete account was not made publicly available until the mid-1980s, and not published until 1992. Reaction to the 1992 publication has varied. Some regard it as a valuable addition to understanding the events, while one historian noted Clausen did not speak to General Walter Short
Walter Short
Walter Campbell Short was a Major General in the United States Army and the U.S. military Commander responsible for the defense of U.S. military installations in Hawaii at the time of the Japanese attack on Pearl Harbor on December 7, 1941.-Early life:He was born in 1880 in Fillmore, Illinois...
, Army commander at Pearl Harbor during the attack, and called Clausen's investigation "notoriously unreliable" in several aspects.
Assertions that Japanese codes had already been broken
U.S. signals intelligence in 1941 was both impressively advanced and uneven. In the past, the U.S. MI-8Black Chamber
The Cipher Bureau otherwise known as The Black Chamber was the United States' first peacetime cryptanalytic organization, and a forerunner of the National Security Agency...
cryptographic operation in New York City had been shut down by Henry Stimson (Hoover's newly appointed Secretary of State), citing "ethical considerations", which inspired its now broke former director, Herbert Yardley
Herbert Yardley
Herbert Osborne Yardley was an American cryptologist best known for his book The American Black Chamber . The title of the book refers to the Cipher Bureau, the cryptographic organization of which Yardley was the founder and head...
, to write a 1931 book, The American Black Chamber, about its successes in breaking other nations' crypto traffic. Most countries responded promptly by changing (and generally improving) their ciphers and codes, forcing other nations to start over in reading their signals. The Japanese were no exception.
Nevertheless, U.S. cryptanalytic work continued after Stimson's action in two separate efforts: the Army's Signal Intelligence Service (SIS) and the Navy's Office of Naval Intelligence (ONI) crypto group, OP-20-G
OP-20-G
OP-20-G or "Office of Chief Of Naval Operations , 20th Division of the Office of Naval Communications, G Section / Communications Security", was the US Navy's signals intelligence and cryptanalysis group during World War II. Its mission was to intercept, decrypt, and analyze naval communications...
. Cryptanalytic work was kept secret to such an extent, however, commands such as the 14th Naval District at Pearl Harbor were prohibited from working on codebreaking by Admiral Kelly Turner as a consequence of the bureaucratic infighting in Washington.
By late 1941, those organizations had broken several Japanese ciphers, such as J19 and PA-K2, called Tsu and Oite respectively by the Japanese. The highest security diplomatic code, dubbed Purple by the U.S., had been broken, but American cryptanalysts had made little progress against the IJN's current Kaigun Ango Sho D (Naval Code D, called AN-1 by the U.S.; JN-25 after March 1942).
In addition, there was a perennial shortage of manpower, thanks to penury on one hand and the perception of intelligence as a low-value career path on the other. Translators were over-worked, cryptanalysts in short supply, staff generally stressed. Furthermore, there were difficulties retaining good intelligence officers and trained linguists; most did not remain on the job for the extended periods necessary to become truly professional. For career reasons, nearly all wanted to return to more standard assignments. However, concerning the manning levels, "... just prior to World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
, [the US] had some 700 people engaged in the effort and [was], in fact, obviously having some successes." Of these, 85% were tasked to decryption and 50% to translation efforts against IJN codes. The nature and degree of these successes has led to great confusion among non-specialists. Furthermore, OP-20-GY "analysts relied as much on summary reports as on the actual intercepted messages."
The U.S. was also given decrypted messages by Dutch (NEI) intelligence, who like the others in the British-Dutch-U.S. agreement to share the cryptographic load, shared information with allies. The U.S. refused to do likewise. This was, at least in part, due to fears of compromise; sharing even between Navy and Army was restricted. The eventual flow of intercepted and decrypted information was tightly and capriciously controlled. At times, even President Roosevelt did not receive all information from code-breaking activities. There were fears of compromise as a result of poor security after a memo dealing with Magic
Magic (cryptography)
Magic was an Allied cryptanalysis project during World War II. It involved the United States Army's Signals Intelligence Section and the United States Navy's Communication Special Unit. -Codebreaking:...
was tossed in the wastebasket of Brigadier General Edwin M. (Pa) Watson, the President's military aide.
Purple
The break into Purple was a considerable cryptographicCryptography
Cryptography is the practice and study of techniques for secure communication in the presence of third parties...
triumph, and proved quite useful later in the War. It was the highest security Japanese Foreign Office system, but prior to Pearl Harbor carried little information about Japanese plans; the military, who were essentially determining foreign policy for Japan, distrusted the Foreign Office and left it "out of the loop". Unfortunately for the U.S., the two U.S. crypto groups generally competed rather than cooperated, and distribution of intelligence from the military to U.S. civilian policy-level officials was poorly done (eg, capriciously selected for distribution) by both the Army and Navy who handled the traffic on alternate days, and furthermore in a way preventing any of its recipients from developing a larger sense of the meaning of the decrypts. Along with the obsession with security, there was little or no analysis done for recipients. Decrypts were typically provided raw, completely without context, and without much taking into account the needs of the recipients. As well, recipients were not permitted to retain them, or notes made from them, again for security reasons.
Most unfortunately, to date not all Purple messages have been released. This was noted as long ago as the Joint Congressional Hearings during the "Magic" testimony. This known fact is often missed, as well as other curious items, for example, the Hearing's questions regarding the missing 25 pages from the Roberts Commission report. Blanket or un-qualified statements on what decoded "Magic" messages revealed are, therefore, premature.
JN-25
The JN-25JN-25
The vulnerability of Japanese naval codes and ciphers was crucial to the conduct of World War II, and had an important influence on foreign relations between Japan and the west in the years leading up to the war as well...
superencrypted code is one of the most debated portions of Pearl Harbor lore. JN-25 is the U.S. Navy's final term for the cryptosystem
Cryptosystem
There are two different meanings of the word cryptosystem. One is used by the cryptographic community, while the other is the meaning understood by the public.- General meaning :...
the Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...
sometimes referred to as Naval Code D. Other names used for it include five-numeral, 5Num, five-digit, five-figure, AN (JN-25 Able), and AN-1 (JN-25 Baker), and so on. It was an example of the then state of the art in crypto systems and was quite different from modern forms of message encryption
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
in being a code (e.g., battleship = 63982) and further being superenciphered with an additive cypher, taken from a large book. So, for example, 63982 + 12345 = 75227 (using modulo arithmetic, non-carrying addition and non-borrowing subtraction, also called Fibonacci
Fibonacci
Leonardo Pisano Bigollo also known as Leonardo of Pisa, Leonardo Pisano, Leonardo Bonacci, Leonardo Fibonacci, or, most commonly, simply Fibonacci, was an Italian mathematician, considered by some "the most talented western mathematician of the Middle Ages."Fibonacci is best known to the modern...
or "Chinese" addition), giving the actually transmitted group (75227); on receipt the additive was subtracted (75227 - 12345 = 63982 (modulo arithmetic again)) and the code group looked up in the current JN-25 code book. The worth of the additive step is that the next time anyone mentioned 'battleship', a different additive would be used. It was based upon the Japanese syllabary (kana
Kana
Kana are the syllabic Japanese scripts, as opposed to the logographic Chinese characters known in Japan as kanji and the Roman alphabet known as rōmaji...
), due to the difficulties in using kanji
Kanji
Kanji are the adopted logographic Chinese characters hanzi that are used in the modern Japanese writing system along with hiragana , katakana , Indo Arabic numerals, and the occasional use of the Latin alphabet...
in telegraphy and the fact that teleprinter
Teleprinter
A teleprinter is a electromechanical typewriter that can be used to communicate typed messages from point to point and point to multipoint over a variety of communication channels that range from a simple electrical connection, such as a pair of wires, to the use of radio and microwave as the...
s were more or less easily converted (e.g., more characters in the syllabary) to kana from the Roman alphabet.
Superenciphered codes of this sort were widely used and were the state of the art in practical cryptography of the time. JN-25 was very similar in principle to the British "Naval Cypher No. 3", known to have been broken by Germany during World War II.
Once it was realized what sort of cryptosystem JN-25 was, the cryptanalytic approach was known. Stinnett, in fact, notes the existence of a USN handbook for attacks on such a system, produced by OP-20-G. Even so, breaking it was not easy in actual practice. It took much effort and time, not least in accumulating sufficient depth in intercepted messages prior to the outbreak of hostilities when IJN radio traffic increased abruptly and substantially; prior to 7 December 1941, IJN radio traffic was limited, since the IJN played only a minor role in the war against China
Second Sino-Japanese War
The Second Sino-Japanese War was a military conflict fought primarily between the Republic of China and the Empire of Japan. From 1937 to 1941, China fought Japan with some economic help from Germany , the Soviet Union and the United States...
and therefore was only rarely required to send radio messages in their highest level crypto system. (As well, interception of IJN traffic off China would have been at best spotty.) Rather oddly however, the official history of GYP-1 shows nearly 45,000 IJN messages intercepted during the period from 1 June 1941 until 4 December 1941. Thus, most Japanese encrypted broadcast military radio traffic was Army traffic associated with the land operations in China.
Breaking a superencrypted cipher like JN-25 was a three-step process: (a) determining the "indicator" method to establish the starting point within the additive cipher, (b) stripping away the superencryption to expose the bare code, and then (c) breaking the code itself. When JN-25 was first detected and recognized, such intercepted messages as were interceptable were collected (at assorted intercept stations around the Pacific by the Navy) in an attempt to accumulate sufficient depth to attempt to strip away the superencryption. Success at doing so was termed by the cryptographers a 'break' into the system. Such a break did not produce a cleartext version of the intercepted message. Only after breaking the underlying code (another difficult process) would the message be available, and even then its meaning—in an intelligence sense—might be less than fully clear.
When a new edition was released, the cryptographers were forced to start again. The original JN-25A system replaced the 'Blue' code (as Americans called it), and used five-digit numbers, each divisible by three (and so usable as a quick, and somewhat reliable, error check, as well as something of a 'crib' to cryptanalysts), giving a total of 33,334 legal code values. To make it harder to crack a code value, meaningless additives (from a large table or book of five-digit numbers) were added arithmetically to each five-digit cipher. JN-25B superseded the first release of JN-25 at the start of December 1940. JN-25B had 55,000 valid words, and while it initially used the same additive list, this was soon changed and the cryptanalysts found themselves entirely blacked out again.
Over the years, various claims have been made as to the progress made decrypting this system, and arguments made over when it was readable (in whole or part). Lt. "Honest John" Leitwiler, Commander of Station CAST
Station CAST
Station CAST was the United States Navy signals monitoring and cryptographic intelligence fleet radio unit at Cavite Navy Yard in the Philippines, until Cavite was captured by the Japanese forces in 1942, during World War II. It was an important part of the Allied intelligence effort, addressing...
, the Philippines, stated in November 1941 that his staff could “walk right across” the number columns of the coded messages. He is frequently quoted in support of claims JN-25 was then mostly readable. This comment, however, refers not to the message itself but to the superenciphering additives and referred to the ease of attacking the code using a new method for discovery of additive values.
The 16 November 1941 letter to L.W. Parks (OP-20-GY) sent by Leitwiler states, "We have stopped work on the period 1 February to 31 July as we have all we can do to keep up with the current period. We are reading enough current traffic to keep two translators very busy." Another document, Exhibit No. 151 (Memoranda from Captain L. F. Safford) from the Hewitt Inquiry has a copy of the U.S. Navy message OPNAV-242239 'Evaluation of Messages of 26 November 1941' which has in part: '1. Reference (a) advised that Com 16 intercepts were considered most reliable and requested Com 16 to evaluate reports on Japanese naval movements and send dispatch to OPNAV, info CINCPAC. Com 16's estimates were more reliable than Com 14's, not only because of better radio interception, but because Com 16 was currently reading messages in the Japanese Fleet Cryptographic System ("5-number code" or "JN25") and was exchanging technical information and Japanese-to-English translations with the British C. I. Unit at Singapore. Lt. Cdr. Arthur H. McCollum knew this and gave it due consideration when he drafted the McCollum memo
McCollum memo
The McCollum memo, also known as the Eight Action Memo was a memorandum, dated October 7, 1940 The McCollum memo, also known as the Eight Action Memo was a memorandum, dated October 7, 1940 The McCollum memo, also known as the Eight Action Memo was a memorandum, dated October 7, 1940 (more than a...
. Duane L. Whitlock, traffic analyst at CAST, was not aware before the attack that IJN movement traffic code was being read. "Reading" in this context means being able to see the underlying code groups, not breaking out the messages into plaintext
Plaintext
In cryptography, plaintext is information a sender wishes to transmit to a receiver. Cleartext is often used as a synonym. Before the computer era, plaintext most commonly meant message text in the language of the communicating parties....
. The Hewitt Inquiry document also states, "The "5 numeral system" (JN-25B) yielded no information which would arouse even a suspicion of the Pearl Harbor raid, either before or afterward."
The claim no pre-attack IJN message expressly mentioned Pearl Harbor is perhaps true. Similarly are the claims no Purple traffic likewise pointed to Pearl Harbor. To note, however, in both instances neither all traffic (IJN nor Purple) from these pre-attack intercepts have been declassified and released to the public domain. Hence, any such claims are now indeterminate, pending a fuller accounting.
Additionally, no decrypts have come to light of JN-25B traffic, and importantly identified as such, with any intelligence value prior to Pearl Harbor. Such breaks as recorded by authors W.J. Holmes and Clay Blair, Jr., were into the additive tables, which was a required first step of two. The first 100 JN-25 decrypts from all sources in date/time order of translation have been released, and are available in the National Archives
National Archives and Records Administration
The National Archives and Records Administration is an independent agency of the United States government charged with preserving and documenting government and historical records and with increasing public access to those documents, which comprise the National Archives...
. The first JN-25B decrypt was in fact by HYPO
Station HYPO
Station HYPO, also known as Fleet Radio Unit Pacific was the United States Navy signals monitoring and cryptographic intelligence unit in Hawaii during World War II. It was one of two major Allied signals intelligence units, called Fleet Radio Units in the Pacific theaters, along with FRUMEL in...
(Hawaii) on 8 January 1942 (numbered #1 up JN-25B RG38 CNSG Library, Box 22, 3222/82 NA CP). The first 25 decrypts were very short messages or partial decrypts of marginal intelligence value. As Duane Whitlock stated, "The reason that not one single JN-25 decrypt made prior to Pearl Harbor has ever been found or declassified is not due to any insidious cover-up... it is due quite simply to the fact that no such decrypt ever existed. It simply was not within the realm of our combined cryptologic capability to produce a usable decrypt at that particular juncture."
Detailed month by month progress reports have shown no reason to believe any JN-25B messages were fully decrypted before the start of the war. Tallied results for September, October, and November reveal roughly 3,800 code groups (out of 55,000, about 7%) had been recovered by the time of the attack on Pearl Harbor.
Detection of Japanese transmissions
There are claims that as the Kido Butai (the Striking Force), steamed toward Hawaii, radio signals were detected that alerted U.S. intelligence to the imminent attack. For instance, the MatsonMatson Navigation Company
The Matson Navigation Company, a subsidiary of Alexander & Baldwin, is a private shipping company with roots extending into the late 19th century...
liner , heading from San Francisco to Hawaii on its regular route, is said to have heard and plotted via "relative bearing
Relative bearing
In nautical navigation the relative bearing of an object is the clockwise angle in degrees from the heading of the vessel to a straight line drawn from the observation station on the vessel to the object....
s" unusual radio traffic, in a telegraphic code very different from International Morse which persisted for several days, and came from signal source(s) moving in an easterly direction, not shore stations - presumably the approaching Japanese fleet. There are numerous Morse Code
Morse code
Morse code is a method of transmitting textual information as a series of on-off tones, lights, or clicks that can be directly understood by a skilled listener or observer without special equipment...
standards including those for Japanese, Korean, Arabic, Hebrew, Russian, and Greek. To the experienced radio operator, each has a unique and identifiable pattern. For example, kana, International Morse, and "Continental" Morse all have a specific rhythmic sound to the "dit" and "dah" combinations. This is how Lurlines radiomen, Leslie Grogan, a U.S. Navy reserve officer in naval communications, and with decades of maritime service in the Pacific identified the mooted signal source as Japanese and not, say, Russian.
There are several problems with this analysis. Surviving officers from the Japanese ships state there was no radio traffic to have been overheard by anyone: their radio operators had been left in Japan to send fake traffic, and all radio transmitters aboard the ships (even those in the airplanes) were physically disabled to prevent any inadvertent or unauthorized broadcast.
The Kido Butai was constantly receiving intelligence and diplomatic updates. Regardless of whether Kido Butai broke radio silence and transmitted, there was a great deal of radio traffic picked up by its antennas. In that time period, it was not unknown for a radio antenna to reflect the energy of an incoming signal back to the ionosphere, where ionospheric skip could result in its reception hundreds or even thousands of miles away. Since the Kido Butai contained a large number of possible reflectors, it thus is conceivable the task force did not break radio silence but was detected anyway.
Such detection would not have helped the Americans track the Japanese fleet. A radio direction finder (DF or RDF) from that time period reported compass direction without reference to distance. (Moreover, it was common for the receiving stations to generate erroneous reciprocal bearings.) To locate the source, a plotter needed two such detections taken from two separate stations to triangulate and find the target. If the target was moving, the detections must be close to one another in time. To plot the task force's course with certainty, at least four such detections must have been made in proper time-pairs, and the information analyzed in light of further information received by other means. This complex set of requirements did not occur; if the Kido Butai was detected, it was not tracked.
According to a 1942 Japanese after action report
After Action Report
An after action report is any form of retrospective analysis on a given sequence of goal-oriented actions previously undertaken, generally by the author himself....
, "In order to keep strict radio silence, steps such as taking off fuses in the circuit, and holding and sealing the keys were taken. During the operation, the strict radio silence was perfectly carried out... The Kido Butai used the radio instruments for the first time on the day of the attack since they had been fixed at the base approximately twenty days before and proved they worked well. Paper flaps had been inserted between key points of some transmitters on board to keep the strictest radio silence..." Commander Genda
Minoru Genda
was a well-known Japanese military aviator and politician. He is best known for planning the Pearl Harbor attack.- Early life :Minoru Genda was the second son of a farmer from Hiroshima. Two brothers were graduates of Tokyo University, another brother graduated from Chiba Medical College, and his...
, who helped plan the attack, stated, "We kept absolute Radio Silence." For two weeks before the attack, the ships of Kido Butai used flag and light signals (semaphore
Flag semaphore
Semaphore Flags is the system for conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags; it is read when the flag is in a fixed position...
and blinker), which were sufficient since task force members remained in line of sight. Kazuiyoshi Koichi, the Communications Officer for , dismantled vital transmitter parts and kept them in a box that he used as a pillow to prevent Hiei from making any radio transmissions until the attack commenced. Lieutenant Commander Chuichi Yoshoka, communications officer of the flagship, Akagi, said he did not recall any ship sending a radio message before the attack. Furthermore, Captain Kijiro, in charge of the Kido Butais three screening submarines, stated nothing of interest happened on the way to Hawaii. Vice Admiral Ryūnosuke Kusaka stated, "It is needless to say that the strictest radio silence was ordered to be maintained in every ship of the Task Force. To keep radio silence was easy to say, but not so easy to maintain." There is nothing in the Japanese logs or after action report indicating that radio silence was broken until after the attack. Kusaka worried about this when it was briefly broken on the way home.
The appendix to the war-initiating operational order is also often debated. The message of 25 November 1941 from CinC Combined Fleet (Yamamoto) to All Flagships stated, "Ships of the Combined Fleet will observe radio communications procedure as follows: 1. Except in extreme emergency the Main Force and its attached force will cease communicating. 2. Other forces are at the discretion of their respective commanders. 3. Supply ships, repair ships, hospital ships, etc., will report directly to parties concerned." Furthermore, "In accordance with this Imperial Operational Order, the CinC of the Combined Fleet issued his operational order ... The Task Force then drew up its own operational order, which was given for the first time to the whole force at Hitokappu Bay... In paragraph four of the appendix to that document, the especially secret Strike Force was specifically directed to 'maintain strict radio silence from the time of their departure from the Inland Sea. Their communications will be handled entirely on the general broadcast communications net.'" In addition, Genda recalled, in a 1947 interview, Kido Butais communications officer issuing this order, with the task force to rely (as might be expected) on flag and blinker.
The original records of Lurline surrendered to Lt. Cmdr. George W. Pease, 14th Naval District in Honolulu, have disappeared. Neither Lurlines log, nor the reports to the Navy or Coast Guard by Grogan in Hawaii can be found. Thus no contemporaneously written evidence of what was recorded aboard Lurline is now available. Grogan commented on a signal source "moving" eastward in the North Pacific over several days as shown via "relative bearings" which then "bunched up" and stopped moving. However, the directions given by Grogan in a recreation of the logbook for the Matson Line were 18 and 44° off from known strike force positions and instead pointed towards Japan. According to author Jacobsen, Japanese commercial shipping vessels are the likely source. A recently discovered missing report by Grogan, dated 10 December 1941 and titled "Record for Posterity", also does not support claims of Kido Butai broadcasting.
The Japanese practiced radio deception
Military deception
Military deception is an attempt to amplify, or create an artificial fog of war or to mislead the enemy using psychological operations, information warfare and other methods. As a form of strategic use of information , it overlaps with psychological warfare...
. Susumu Ishiguru, intelligence and communications officer for Carrier Division Two, stated, "Every day false communications emanated from Kyushu at the same time and same wavelength as during the training period." Because of this, Commander Joseph Rochefort
Joseph Rochefort
Joseph John Rochefort was an American Naval officer and cryptanalyst. His contributions and those of his team were pivotal to victory in the Pacific War....
of Hawaii Signals Intelligence
Station HYPO
Station HYPO, also known as Fleet Radio Unit Pacific was the United States Navy signals monitoring and cryptographic intelligence unit in Hawaii during World War II. It was one of two major Allied signals intelligence units, called Fleet Radio Units in the Pacific theaters, along with FRUMEL in...
concluded that the First Air Fleet remained in home waters for routine training. The ships left their own regular wireless operators to carry on "routine" radio traffic. Captain Sadatoshi Tomioka stated, "The main force in the Inland Sea and the land-based air units carried out deceptive communications to indicate the carriers were training in the Kyushu area." The main Japanese naval bases (Yokosuka, Kure, and Sasebo) all engaged in considerable radio deception. Analysis of the bearings from Navy DF stations account for claimed breaks of radio silence, and when plotted, the bearings point to the Japanese naval bases, not where those ships actually were.
Rochefort, with Huckins and Williams, states there were no dummy messages used at any time throughout 1941 and no effort by the Japanese to use serious deception. When asked after the attack just how he knew where Akagi was, Rochefort (who commanded HYPO at the time) said he recognized her "same ham-fisted" radio operators. (The Japanese contend that radio operators were left behind as part of the deception operation.) The critical DF-tracked radio transmissions show bearings that could have not come from the strike force. Emissions monitored from CAST, or CAST's report Akagi was off Okinawa on 8 December 1941, are examples, though some transmissions continue to be debated. The contention that "low-powered" radio (such as VHF
Very high frequency
Very high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...
or what the U.S. Navy called TBS, or talk between ships), might have been used, and detected, is contradicted as impossible due to the tremendous distances involved and when contact was lost, it was routinely presumed it was because low-powered radio and land line were being used. Freedom of Information Act (FOIA) requests for specific RDF reports remain wanting. "A more critical analysis of the source documentation shows that not one single radio direction finder bearing, much less any locating "fix," was obtained on any Kido Butai unit or command during its transit from Saeki Bay, Kyushu to Hitokappu Bay and thence on to Hawaii. By removing this fallacious lynchpin propping up such claims of Kido Butai radio transmissions, the attendant suspected conspiracy tumbles down like a house of cards."
One suggested example of a Kido Butai transmission is the November 30, 1941 COMSUM14 report in which Rochefort mentioned a "tactical" circuit heard calling "marus"
Japanese ship naming conventions
Japanese ship naming conventions are different from those in the West. Japanese warships have never been named after people. Prior to World War II, Japanese ship naming conventions underwent several changes before being settled.- Merchant ships :...
. (a term often used for commercial vessels or non-combat units). Further, the perspective of U.S. naval intelligence at the time was, "... The significance of the term, 'tactical circuit' is that the vessel itself, that is Akagi, was using its own radio to call up the other vessels directly rather than work them through shore stations via the broadcast method which was the common practice in Japanese communications. The working of the Akagi with the Marus, indicated that she was making arrangements for fuel or some administrative function, since a carrier would rarely address a maru."
Also, from a U.S. Navy radiomen on duty at STATION AE (STATION Able Easy, Sitka, Alaska) at the time of Pearl Harbor, Elmer H. Frantz, states, "It is inconceivable to me that a force represented by the Kido Butai with 33 ships involved of all different types ... and no radio communications, communication black out on orders - I just don't believe it."
One story from author Constantine Fitzgibbon claimed that a letter received from V. F. W. Cavendish-Bentinck stated Britain's JIC met and discussed at length the impending Japanese attack on Pearl Harbor. From a Joint Intelligence Sub-Committee session of 5 December 1941 it was stated "We knew that they changed course. I remember presiding over a J.I.C. meeting and being told that a Japanese fleet was sailing in the direction of Hawaii, asking 'Have we informed our transatlantic brethren?' and receiving an affirmative reply." However the author was incorrect. There was no session on the 5th of Dec nor was Pearl Harbor discussed when they did meet on the 3rd.
Statements by high-ranking officials
One perspective is given by Vice AdmiralVice Admiral
Vice admiral is a senior naval rank of a three-star flag officer, which is equivalent to lieutenant general in the other uniformed services. A vice admiral is typically senior to a rear admiral and junior to an admiral...
Frank E. Beatty
Frank E. Beatty
Rear Admiral Frank Edmund Beatty was an officer in the United States Navy.-Biography:Born in Aztalan, Wisconsin, Beatty graduated with the United States Naval Academy Class of 1875, and then served at sea in the wooden screw-sloop Tuscarora before receiving his ensign's commission in 1876...
, who at the time of the Pearl Harbor attack was an aide to the Secretary of the Navy
United States Secretary of the Navy
The Secretary of the Navy of the United States of America is the head of the Department of the Navy, a component organization of the Department of Defense...
Frank Knox
Frank Knox
-External links:...
and was very close to President Franklin D. Roosevelt
Franklin D. Roosevelt
Franklin Delano Roosevelt , also known by his initials, FDR, was the 32nd President of the United States and a central figure in world events during the mid-20th century, leading the United States during a time of worldwide economic crisis and world war...
's inner circle
Social network
A social network is a social structure made up of individuals called "nodes", which are tied by one or more specific types of interdependency, such as friendship, kinship, common interest, financial exchange, dislike, sexual relationships, or relationships of beliefs, knowledge or prestige.Social...
, with perspicuous remarks as:
"Prior to December 7, it was evident even to me... that we were pushing Japan into a corner. I believed that it was the desire of President Roosevelt, and Prime Minister ChurchillWinston ChurchillSir Winston Leonard Spencer-Churchill, was a predominantly Conservative British politician and statesman known for his leadership of the United Kingdom during the Second World War. He is widely regarded as one of the greatest wartime leaders of the century and served as Prime Minister twice...
that we get into the war, as they felt the Allies could not win without us and all our efforts to cause the Germans to declare war on us failed; the conditions we imposed upon Japan—to get out of China, for example—were so severe that we knew that nation could not accept them. We were forcing her so severely that we could have known that she would react toward the United States. All her preparations in a military way—and we knew their over-all import—pointed that way."
Another "eye witness viewpoint" akin to Beatty's is provided by Roosevelt's administrative assistant at the time of Pearl Harbor, Jonathan Daniels; it is the telling comment about FDR's reaction to the attack - "The blow was heavier than he had hoped it would necessarily be. ... But the risks paid off; even the loss was worth the price. ..."
"Ten days before the attack on Pearl Harbor
Attack on Pearl Harbor
The attack on Pearl Harbor was a surprise military strike conducted by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on the morning of December 7, 1941...
", Henry L. Stimson
Henry L. Stimson
Henry Lewis Stimson was an American statesman, lawyer and Republican Party politician and spokesman on foreign policy. He twice served as Secretary of War 1911–1913 under Republican William Howard Taft and 1940–1945, under Democrat Franklin D. Roosevelt. In the latter role he was a leading hawk...
, United States Secretary of War
United States Secretary of War
The Secretary of War was a member of the United States President's Cabinet, beginning with George Washington's administration. A similar position, called either "Secretary at War" or "Secretary of War," was appointed to serve the Congress of the Confederation under the Articles of Confederation...
at the time "entered in his diary the famous and much-argued statement - that he had met with President Roosevelt to discuss the evidence of impending hostilities with Japan, and the question was 'how we should maneuver them [the Japanese] into the position of firing the first shot without allowing too much danger to ourselves.'" However Stimson, in reviewing his diary after the war, recalled that the commanders at Pearl Harbor had been warned of the possibility of attack, and that the poor state of readiness that the attack had revealed was a surprise to him:
[Yet] General Short had been told the two essential facts: 1) a war with Japan is threatening, 2) hostile action by Japan is possible at any moment. Given these two facts, both of which were stated without equivocation in the message of Nov. 27, the outpost commander should be on the alert to make his fight. . . .
To cluster his airplanes in such groups and positions that in an emergency they could not take the air for several hours, and to keep his antiaircraft ammunition so stored that it could not be promptly and immediately available, and to use his best reconnaissance system, the radar, only for a very small fraction of the day and night, in my opinion betrayed a misconception of his real duty which was almost beyond belief. . . .
Stimson omits to mention the "war warning" message expressly told Short not to alarm the civilian population and to be alert for sabotage, which was widely expected to be a precursor to attack.
Robert Stinnett's Day of Deceit suggests a memorandum
McCollum memo
The McCollum memo, also known as the Eight Action Memo was a memorandum, dated October 7, 1940 The McCollum memo, also known as the Eight Action Memo was a memorandum, dated October 7, 1940 The McCollum memo, also known as the Eight Action Memo was a memorandum, dated October 7, 1940 (more than a...
prepared by Commander McCollum was central to U.S. policy in the immediate pre-war period. Stinnett claims the memo suggests only a direct attack on U.S. interests would sway the American public (or Congress) to favor direct involvement in the European war, specifically in support of the British. An attack by Japan would not, could not, aid Britain, as history would prove. Although the memo was passed to Captains Walter Anderson and Dudley Knox, two of Roosevelt's military advisors, on October 7, 1940, there is no evidence to suggest Roosevelt ever saw it, while Stinnett's claims of evidence he did is nonexistent. Moreover, although Anderson and Knox offered eight specific plans to aggrieve the Japanese Empire and added, "If by these means Japan could be led to commit an overt act of war, so much the better," of the eight "plans" (actions to be taken) offered in the memo, only one was ever implemented in any fashion, and there is considerable doubt the memo was the inspiration. Nonetheless, in Day of Deceit Stinnett claims all action items were implemented. Yet there were numerous instances of members of the Roosevelt Administration insisting on not provoking Japan. Mark Parillo, in his essay The United States in the Pacific, wrote, "[t]hese theories tend to founder on the logic of the situation. Had Roosevelt and other members of his administration known of the attack in advance, they would have been foolish to sacrifice one of the major instruments needed to win the war just to get the United States into it." Furthermore, on 5 November 1941, in a joint memo, Stark
Harold Rainsford Stark
Harold Rainsford Stark served as an officer in the United States Navy during World War I and World War II. Stark was the US Navy's 8th Chief of Naval Operations, from August 1, 1939 to 26 March 1942....
, CNO
Chief of Naval Operations
The Chief of Naval Operations is a statutory office held by a four-star admiral in the United States Navy, and is the most senior uniformed officer assigned to serve in the Department of the Navy. The office is a military adviser and deputy to the Secretary of the Navy...
, and Marshall
George Marshall
George Catlett Marshall was an American military leader, Chief of Staff of the Army, Secretary of State, and the third Secretary of Defense...
, Army Chief of Staff, warned, "if Japan be defeated and Germany remain undefeated, decision will still not have been reached.... War between the United States and Japan should be avoided...." Additionally, in a 21 November 1941 memo, Brigadier Leonard T. Gerow
Leonard T. Gerow
Leonard Townsend Gerow was a United States Army general.-Early life:Gerow was born in Petersburg, Virginia. The name Gerow is derived from the French name "Giraud". Gerow attended high school in Petersburg and then attended the Virginia Military Institute. He was three times elected class...
, head of Army War Plans, stated, "one of our present major objectives [is] the avoidance of war with Japan...[and to] insure continuance of material assistance to the British." He concluded, "[I]t is of grave importance to our war effort in Europe..." Furthermore, Churchill himself, in a 15 May 1940 telegram, said he hoped a U.S. commitment to aid Britain would "quiet" Japan, following with a 4 October message requesting a USN courtesy visit to Singapore aimed at "preventing the spreading of the war" And Stark's own Plan Dog
Plan Dog memo
The Plan Dog memorandum was a 1940 American government document written by Chief of Naval Operations Harold Rainsford Stark, "one of the best known documents of World War II"...
expressly stated, "Any strength that we might send to the Far East would...reduce the force of our blows against Germany..." Roosevelt could scarcely have been ignorant of Stark's views, and war with Japan was clearly contrary to Roosevelt's express wish to aid Britain and with Churchill's to "quiet" Japan.
One quote is often used to add legitimacy to the notion the British Government knew in advance the attack was coming. Oliver Lyttelton, the British Minister of War Production, said, "...Japan was provoked into attacking the Americans at Pearl Harbor. It is a travesty of history ever to say that America was forced into the war. Everyone knows where American sympathies were. It is incorrect to say that America was truly neutral even before America came into the war on an all-out basis." How this demonstrates anything with regard to Japan is unclear. Rather, it refers to other aid to Britain. Lend-Lease
Lend-Lease
Lend-Lease was the program under which the United States of America supplied the United Kingdom, the Soviet Union, China, Free France, and other Allied nations with materiel between 1941 and 1945. It was signed into law on March 11, 1941, a year and a half after the outbreak of war in Europe in...
, enacted in March 1941, informally declared the end of American neutrality in favor of the Allies by agreeing to supply Allied nations with war materials. In addition, Roosevelt authorized a so-called Neutrality Patrol
Neutrality Patrol
At the beginning of World War II, when Nazi Germany's invasion of Poland on 1 September 1939 started the hostilities in Europe, President Franklin D...
, which would protect the merchantmen of one hostile nation, Britain, from attack by another, Germany. This made shipping legitimate target of attack by submarine. Furthermore, Roosevelt ordered U.S. destroyer
Destroyer
In naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...
s to report U-boat
U-boat
U-boat is the anglicized version of the German word U-Boot , itself an abbreviation of Unterseeboot , and refers to military submarines operated by Germany, particularly in World War I and World War II...
s, then later authorized them to "shoot on sight". This made the U.S. a de facto belligerent. None was the act of a disinterested neutral, while all are unquestionably of assistance to Britain.
When considering information like this as a point for or against, the reader must keep in mind questions such as: was this official privy to information about the U.S. government? Did he have communications with high-level administration figures such as President Roosevelt or Ambassador Joseph Grew
Joseph Grew
Joseph Clark Grew was a United States diplomat and career foreign service officer. He was the chargé d'affaires at the U.S. embassy in Vienna when Austria-Hungary severed diplomatic relations with the United States on April 9, 1917. Later he was the U.S. Ambassador to Denmark 1920–1921 and U.S....
? Is this just a strongly held personal opinion? Or were there measures justifying this view? If Britain, did, indeed know and chose to conceal, "withholding this vital intelligence only ran the risk of losing American trust", and with it any further American aid, which would be reduced after the attack in any event.
There is also a claim, first asserted in Toland's Infamy, ONI knew about Japanese carrier movements. Toland cited entries from the diary of Rear Admiral J. E. Meijer Ranneft of the Dutch Navy for 2 December and 6 December. Ranneft attended briefings at ONI on these dates. According to Toland, Ranneft wrote that he was told by ONI that two Japanese carriers were northwest of Honolulu. However, the diary uses the Dutch abbreviation beW, meaning "westerly", contradicting Toland's claim. Nor did any other persons present at the briefings report hearing Toland's version. In their reviews of Infamy, David Kahn and John C. Zimmerman suggested Ranneft's reference was to carriers near the Marshall Islands. Toland has made other conflicting and incorrect claims about the diary during lectures at the Holocaust denial organization the Institute for Historical Review
Institute for Historical Review
The Institute for Historical Review , founded in 1978, is an American organization that describes itself as a "public-interest educational, research and publishing center dedicated to promoting greater public awareness of history." Critics have accused it of being an antisemitic "pseudo-scholarly...
.
The diary states at 02:00 (6-12-41) Turner fears a sudden Japanese attack on Manila. At 14:00 the diary states "Everyone present on O.N.I. I speak to Director Admiral Wilkinson, Captain MacCollum, Lt. Cdr. Kramer...They show me – on my request – the place of the 2 carriers (see 2–12–41) West of Honolulu. I ask what the idea is of these carriers on that place. The answer was: 'perhaps in connection with Japanese rapports [sic] on eventual American actions'. There is not one of ours who speaks about a possible air attack on Honolulu. I myself did not think of it because I believed everyone on Honolulu to be 100% on the alert, as everyone here on O.N.I. There prevails a tense state of mind at O.N.I." These diary entries are provided (in Dutch) in the photo section in George Victor's The Pearl Harbor Myth: Rethinking the Unthinkable.
The McCollum memo
Lieutenant Commander
Lieutenant Commander is a commissioned officer rank in many navies. The rank is superior to a lieutenant and subordinate to a commander...
Arthur H. McCollum of the Office of Naval Intelligence
Office of Naval Intelligence
The Office of Naval Intelligence was established in the United States Navy in 1882. ONI was established to "seek out and report" on the advancements in other nations' navies. Its headquarters are at the National Maritime Intelligence Center in Suitland, Maryland...
submitted a memo to Navy Captains Walter S. Anderson and Dudley Knox, which details eight actions which might have the effect of provoking Japan into attacking the United States. The memo remained classified
Classified information
Classified information is sensitive information to which access is restricted by law or regulation to particular groups of persons. A formal security clearance is required to handle classified documents or access classified data. The clearance process requires a satisfactory background investigation...
until 1994.
Sections 9 and 10 of the memo are cited as the "smoking gun", and a primary thesis of Stinnett's book, suggesting it was central to the high level conspiracy
Conspiracy (civil)
A civil conspiracy or collusion is an agreement between two or more parties to deprive a third party of legal rights or deceive a third party to obtain an illegal objective....
to lure the Japanese into an attack. Evidence the memo or derivative works actually reached President Roosevelt, senior administration officials, or the highest levels of U.S. Navy command, is largely conjectural.
In actuality, Stinnett attributes to McCollum a position McCollum expressly refuted. Furthermore, McCollum's own sworn testimony also refutes it.
Japanese intelligence
Japanese espionage against Pearl Harbor involved at least two AbwehrAbwehr
The Abwehr was a German military intelligence organisation from 1921 to 1944. The term Abwehr was used as a concession to Allied demands that Germany's post-World War I intelligence activities be for "defensive" purposes only...
agents. One of them, Otto Kuhn, was a sleeper agent
Sleeper agent
A sleeper agent is a spy who is placed in a target country or organization, not to undertake an immediate mission, but rather to act as a potential asset if activated...
living in Hawaii with his family. Kuhn was incompetent and there is no evidence he provided information of value. The other, Yugoslavia
Yugoslavia
Yugoslavia refers to three political entities that existed successively on the western part of the Balkans during most of the 20th century....
n businessman Dusko Popov, was a double agent, working for the XX Committee of MI5
MI5
The Security Service, commonly known as MI5 , is the United Kingdom's internal counter-intelligence and security agency and is part of its core intelligence machinery alongside the Secret Intelligence Service focused on foreign threats, Government Communications Headquarters and the Defence...
. In August 1941, he was sent by the Abwehr to the U.S., with an assignment list that included specific questions about military facilities in Oahu, including Pearl Harbor. The FBI seems to have paid little attention. J. Edgar Hoover
J. Edgar Hoover
John Edgar Hoover was the first Director of the Federal Bureau of Investigation of the United States. Appointed director of the Bureau of Investigation—predecessor to the FBI—in 1924, he was instrumental in founding the FBI in 1935, where he remained director until his death in 1972...
dismissed Popov as unimportant, and there is nothing to show his assignment list was passed on to military intelligence, nor was he allowed to visit Hawaii. Popov later asserted his list was a clear warning of the attack, ignored by the bungling FBI. The questions in his list were rambling and general, and in no way pointed to air attack on Pearl Harbor, & Prange considered Popov's claim overblown, and argued the notorious questionnaire was a product of Abwehr thoroughness.
Another intended agent was the highly decorated former RAF Squadron-
Leader Frederick Joseph Rutland who helped the Japanese navy develop aircraft
carriers in the 1920s, and in the 1930s was deployed as a secret agent in the
USA. But for problems with establishing his cover in Hawaii as a whisky
importer, Rutland would have been the key Japanese naval intelligence spy
supporting the attack on Pearl Harbor in December 1941.
Furthermore, the Japanese did not need Abwehr assistance, having a consulate in Hawaii which had on its staff an undercover IJN intelligence officer, Takeo Yoshikawa
Takeo Yoshikawa
was a Japanese spy in Hawaii before the attack on Pearl Harbor on December 7, 1941.-Early career:A 1933 graduate of the Imperial Japanese Naval Academy at Etajima , Yoshikawa served briefly at sea aboard the armored cruiser Asama as well as submarines and had begun training as a naval pilot near...
. The consulate had reported to IJN Intelligence for years, and Yoshikawa increased the rate of reports after his arrival. (Sometimes called a "master spy", he was in fact quite young, and his reports not infrequently contained errors.) Pearl Harbor base security was so lax Yoshikawa had no difficulty obtaining access, even taking the Navy's own harbor tourboat. (Even had he not, hills overlooking the Harbor were perfect for observation or photography, and were freely accessible.) Gossip with taxi drivers is supposed to have been one of his sources as well. Some of his information, and presumably other material from the Consulate, was hand-delivered to IJN intelligence officers aboard Japanese commercial vessels calling at Hawaii prior to the War; at least one is known to have been deliberately routed to Hawaii for this purpose during the summer. Most, however, seem to have been transmitted to Tokyo, almost certainly via cable (the usual communication method with Tokyo). Many of those messages were intercepted and decrypted by the U.S.; most were evaluated as routine intelligence gathering all nations do about potential opponents, rather than evidence of an active attack plan. None of those currently known, including those decrypted after the attack when there was finally time to return to those remaining undecrypted, explicitly stated anything about an attack on Pearl Harbor. The only exception was a message sent from the Hawaiian Consulate on 6 December, which was not decrypted until after the 7th, making it moot with respect to U.S. foreknowledge. No cable traffic was intercepted in Hawaii until after David Sarnoff
David Sarnoff
David Sarnoff was an American businessman and pioneer of American commercial radio and television. He founded the National Broadcasting Company and throughout most of his career he led the Radio Corporation of America in various capacities from shortly after its founding in 1919 until his...
of RCA
RCA
RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...
agreed to assist during a visit to Hawaii immediately before the 7th. Such interception was illegal under U.S. law, though it had been going on sub rosa
Sub rosa
The Latin phrase sub rosa means "under the rose" and is used in English to denote secrecy or confidentiality, similar to the Chatham House Rule....
in New York for some time. Farago's postscript offers a viewpoint from RCA personnel. In the final analysis, illegal co-operation of American cable companies changed little or nothing, since radio intercept stations were picking up some of the consular traffic anyway, and American intelligence failed to make optimum use of the information in any case.
Allied intelligence
Locally, Naval Intelligence in Hawaii had been tapping telephones at the Japanese Consulate before the 7th. Among much routine traffic was overheard a most peculiar discussion of flowers in a call to Tokyo (the significance of which is still publicly opaque and which was discounted in Hawaii at the time), but the Navy's tap was discovered and removed in the first week of December. The local FBI field office was informed of neither the tap nor its removal; the local FBI Agent in charge later claimed he would have had installed one of his own had he known the Navy's had been disconnected.Throughout 1941, the U.S., Britain, and the Netherlands collected considerable evidence suggesting Japan was planning some new military adventure. The Japanese attack on the U.S. in December was essentially a side operation to the main Japanese thrust to the South against Malaya
British Malaya
British Malaya loosely described a set of states on the Malay Peninsula and the Island of Singapore that were brought under British control between the 18th and the 20th centuries...
and the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
—many more resources, especially Imperial Army resources, were devoted to these attacks as compared to Pearl Harbor. Many in the Japanese military (both Army and Navy) had disagreed with Admiral Isoroku Yamamoto
Isoroku Yamamoto
was a Japanese Naval Marshal General and the commander-in-chief of the Combined Fleet during World War II, a graduate of the Imperial Japanese Naval Academy and a student of Harvard University ....
's idea of attacking the U.S. Fleet at Pearl Harbor when it was first proposed in early 1941, and remained reluctant after the Navy approved planning and training for an attack beginning in spring 1941, and through the highest level Imperial Conferences in September and November which first approved it as policy (allocation of resources, preparation for execution), and then authorized the attack. The Japanese focus on South-East Asia was quite accurately reflected in U.S. intelligence assessments; there were warnings of attacks against Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
(the Kra Peninsula), Malaya, French Indochina
French Indochina
French Indochina was part of the French colonial empire in southeast Asia. A federation of the three Vietnamese regions, Tonkin , Annam , and Cochinchina , as well as Cambodia, was formed in 1887....
, the Dutch East Indies
Dutch East Indies
The Dutch East Indies was a Dutch colony that became modern Indonesia following World War II. It was formed from the nationalised colonies of the Dutch East India Company, which came under the administration of the Netherlands government in 1800....
(Davao-Weigo Line), the Philippines, even Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
. Pearl Harbor was not mentioned. In fact, when the final part of the "14-Part Message" (also called the "one o'clock message") crossed Kramer's desk, he cross-referenced the time (per usual practice, not the brainwave often portrayed) and tried to connect the timing to a Japanese convoy (the Thai invasion force) recently detected by Admiral Hart
Thomas C. Hart
Thomas Charles Hart was an admiral of the United States Navy, whose service extended from the Spanish-American War through World War II. Following his retirement from the Navy, he served briefly as a United States Senator from Connecticut.-Life and career:Hart was born in Genesee County, Michigan...
in the Philippines.
The U.S. Navy was aware of the traditional planning of the Imperial Japanese Navy for war with the U.S., as maintained throughout the 1930s and into the 1940s. The Japanese made no secret of it, and in the 1930s American radio intelligence gave U.S. war planners considerable insight in Japanese naval exercises. These plans presumed there would be a large decisive battle between Japanese and U.S. battleships, but this would be fought near Japan, after the numerical superiority of the U.S. Pacific Fleet (assured by the Washington Naval Treaty
Washington Naval Treaty
The Washington Naval Treaty, also known as the Five-Power Treaty, was an attempt to cap and limit, and "prevent 'further' costly escalation" of the naval arms race that had begun after World War I between various International powers, each of which had significant naval fleets. The treaty was...
, and still taken as given) was whittled down by primarily night attacks by light forces, such as destroyers and submarines. This strategy expected the Japanese fleet to take a defensive posture, awaiting U.S. attack, and it was confirmed by the Japanese Navy staff only three weeks before Pearl Harbor. In the 1920s, the decisive battle was supposed to happen near the Ryukyu islands; in 1940 it was expected to occur in the central Pacific, near the Marshall islands. War Plan Orange
War Plan Orange
War Plan Orange refers to a series of United States Joint Army and Navy Board war plans for dealing with a possible war with Japan during the years between the First and Second World Wars....
reflected this in its own planning for an advance across the Pacific. Yamamoto's decision to shift the focus of the confrontation with the U.S. as far east as Pearl Harbor, and to use his aircraft carriers to cripple the American battleships, was a radical enough departure from previous doctrine to leave analysts in the dark.
There had been a specific claim of a plan for an attack on Pearl Harbor from the Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
vian Ambassador to Japan in early 1941. (The source of this intelligence was traced to the Ambassador's Chinese cook. It was treated with skepticism, and properly so, given the nascent state of planning for the attack at the time and the unreliability of the source.) Since Yamamoto had not yet decided to even argue for an attack on Pearl Harbor, discounting Ambassador Grew's report to Washington in early 1941 was quite sensible. Later reports from a Korean labor organization also seem to have been regarded as unlikely, though they may have had better grounding in actual IJN actions. There has been uncovered no record of a serious belief or conviction by anyone in U.S. or UK military intelligence (in Hawaii, DC or elsewhere), or among U.S. civilian policy officials, prior to the attack, of Pearl Harbor or the U.S. West Coast as a potential target.
Notices to Japanese foreign stations – the Winds Code message
The "Winds CodeWinds Code
The “Winds Code” is a confused military intelligence episode relating to the Attack on Pearl Harbor, especially the advance-knowledge debate.The Winds Code was an instruction from Tokyo to the Japanese embassy in Washington on November 19, 1941...
" announcing the direction of new hostilities via a broadcast weather 'forecast', remains a curious and confusing episode, demonstrating the uncertain meaning inherent in most raw intelligence information, and its handling/mis-handling - and in this case, even uncertainty about the existence of some intelligence information, or of its active removal from official records, especially some years after the event.
At most, however, the Winds system was to be implemented only if the communications between Japan and Washington were cut, and since this never obtained prior to the attack, there was no need for it. Given this, any talk of intercepted "Winds" messages would appear to be specious. Note, however, in Safford's testimony on this topic he states very clearly London (not Washington) was the addressee of this message.
There are two problems with this evaluation. First, there is Admiral King's endorsement of the Navy Court of Inquiry, page 344, reading in part, " ... (3) Admiral Kimmel was not informed of the implementation of the "Winds Message". Admiral Stark says he never got this information himself, but it is clear that it did reach Admiral Stark's office. This, together with the handling of other matters of information, indicates some lack of efficiency in Admiral Stark's organization. ..." Second, there exists more documentation for the "Winds Execute" which relates an account of interception of the "Winds Execute", passing the message to ONI, and later, his direct order from Captain Harper not to testify in support of Safford at one of the Pearl Harbor hearings. Also see RG457 SRH-255 Archives II College Park MD where Ogg's statements during an interview by Captain Irwin G. Newman were considerably different from Toland's attributions and amplified by authors Stinnett and Wilford, and where neither Ogg or Newman ever mention the Winds code topic.
Official U.S. war warnings
In late November 1941, both the U.S. Navy and Army sent explicit war with Japan warnings to all Pacific commands. Although these plainly stated the high probability of imminent war with Japan, and instructed recipients to be accordingly on alert for war, they did not mention the likelihood of an attack on Pearl Harbor itself, instead focusing on the Far East. Washington forwarded none of the raw intelligence it had, and little of its intelligence estimates (after analysis), to Hawaiian commanders, Admiral Husband E. KimmelHusband E. Kimmel
Husband Edward Kimmel was a four-star admiral in the United States Navy. He served as Commander-in-chief, U.S. Pacific Fleet at the time of the Japanese attack on Pearl Harbor. Because of the attack, he was removed from office and was reduced to his permanent two-star rank of rear admiral...
and General Walter C. Short
Walter Short
Walter Campbell Short was a Major General in the United States Army and the U.S. military Commander responsible for the defense of U.S. military installations in Hawaii at the time of the Japanese attack on Pearl Harbor on December 7, 1941.-Early life:He was born in 1880 in Fillmore, Illinois...
. Washington did not solicit their views about likelihood of war or Hawaiian special concerns. Washington's war warning messages have also been criticised by some (e.g., the U.S. Army Pearl Harbor Board - "Do/Don't Messages") as containing "conflicting and imprecise" language.
Since the Army was officially responsible for the security of the Pearl Harbor facilities and Hawaiian defense generally, and so of the Navy's ships while in port, Army actions are of particular interest. Short reported to Washington he had increased his alert level (but his earlier change in meaning for those levels was not understood in Washington and led to misunderstanding there about what he was really doing). In addition, Short's main concern was sabotage from fifth columnists (expected to precede the outbreak of war for decades preceding the attack), which accounts for his orders that Army Air Corps planes be parked close together near the center of the airfields. There seems to have been no increased Army urgency about getting its existing radar equipment properly integrated with the local command and control in the year it had been available and operational in Hawaii before the attack. Leisurely radar training continued and the recently organized early warning center was left minimally staffed. Anti-aircraft guns remained in a state of low readiness, with ammunition in secured lockers. Neither Army long range bombers nor Navy PBYs were used effectively, remaining on a peacetime maintenance and use schedule. Short evidently failed to understand he had the responsibility to defend the fleet. In Short's defense, it should be noted he had training responsibilities to meet, and the best patrol aircraft, B-17s and B-24s, were in demand in the Philippines and Britain, both of which had higher priority.
Little was done to prepare for air attack. Inter-service rivalries
Interservice rivalry
Interservice rivalry is a military term referring to rivalries that can arise between different branches of a country's armed forces, such as between a nation's land forces , naval and air forces. It also applies to the rivalries between a country's intelligence services, Central Intelligence...
between Kimmel and Short did not improve the situation. Particularly, most intelligence information was sent to Kimmel, assuming he would relay it to Short, and vice versa; this assumption was honored mostly in the breach. Hawaii did not have a Purple cipher machine (although, by agreement at the highest levels between U.S. and UK cryptographic establishments, four had been delivered to the British by October 1941), so Hawaii remained dependent on Washington for intelligence from that (militarily limited) source. However, since Short had no liaison with Kimmel's intelligence staff, he was usually left out of the loop. Henry Clausen
Henry Clausen
Henry Christian Clausen was the author of the Clausen Report, an 800-page report on the Army Board’s Pearl Harbor Investigation. He traveled over 55,000 miles over seven months in 1945, and interviewed nearly a hundred personnel, Army, Navy, British and civilian, as a Special Investigator for the...
reported the war warnings could not be more precise because Washington could not risk Japan guessing the U.S. was reading important parts of their traffic (i.e., most importantly Purple, despite the fact there was no known tactical or strategic info in that traffic), as well as the fact neither was cleared to receive Purple; Clausen does not answer why Washington could not have said "an exceptionally reliable source" was involved, with very strong instructions to pay attention.
Additionally, Clausen claims military men of Kimmel and Short's seniority and background should have understood the significance of the warnings, and should have been more vigilant than they were, as for instance in scouting plane flights from Hawaii, which were partial at best in the period just before the attack. All other Pacific commands took appropriate measures for their situations.
Like most commentators, Clausen ignores what the "war warnings" (and their context) explicitly warn, though indistinctly, against. Washington, with more complete intelligence than any field command, expected an attack anywhere on a list of possible locations (Pearl Harbor not among them), and since the Japanese were already committed to Thailand, it seems to have been expected another major operation by them was impossible. Clausen, like most, also ignores what actions Kimmel, Short, and Admiral Claude C. Bloch
Claude C. Bloch
Admiral Claude Charles Bloch was a United States Navy admiral who served as Commander, Battle Force, U.S. Fleet from 1937–1938; and Commander in Chief, U.S. Fleet from 1938-1940.-Biography:...
(Commander, Fourteenth Naval District, responsible for naval facilities in Hawaii) actually took. They took precautions against sabotage, widely expected as a precursor to war, and reported their preparations. The Hawaii commanders did not anticipate an air attack; no one did so explicitly. Indeed, the prevailing view at the time was Japan could not execute two major naval operations at once, so with the Thailand invasion convoy known to be at sea, the Hawaii commanders had good reason to feel safe.
One major point often omitted from the debate (though Costello covers it thoroughly) is the Philippines, where MacArthur, unlike Kimmel or Short, had complete access to all decrypted Purple and JN-25 traffic CAST could provide (indeed, Stinnet quotes Whitlock to that effect), and was nonetheless caught unprepared and with all planes on the ground nevertheless, nine hours after the Pearl Harbor attack. Caidin and Blair also raise the issue.
Although it has been argued that there was sufficient intelligence at the time to give commanders at Pearl Harbor a greater level of alert, some factors may take on unambiguous meaning not clear at the time, lost in what Roberta Wohlstetter in her masterful examination of the situation called "noise", "scattered amid the dross of many thousands of other intelligence bits, some of which just as convincingly pointed to a Japanese attack on the Panama Canal."
"Inherent invulnerability" of Pearl Harbor
One of the main considerations making an attack against Pearl Harbor unimaginable to many was the depth of Pearl Harbor—generally less than 40 ft (12.2 m). Depths of less than 150 ft (45.7 m) had been (in the U.S. Navy and others) widely believed insufficient for torpedo attack; at the time, a torpedo dropped from a plane dove deeply before attaining running depth, and in water that was not deep enough (like Pearl Harbor) would contact the bottom, detonating or embedding itself in the mud.Not all in the U.S. Navy shared this opinion. A mock air attack on Pearl Harbor during war games in the 1930s was judged to have been a success. Shortly after taking office, Navy Secretary Knox wrote an overview memo which specifically noted the possibility of an attack at Pearl Harbor. However, neither observation led to formal policy recommendations to forestall such an attack. Admiral James O. Richardson, who was fired by President Roosevelt for refusing to station the Pacific Fleet in Pearl Harbor, blamed the President for the "initial defeats in the Pacific" as "direct, real and personal." Richardson believed stationing the fleet in Pearl Harbor made the ships extremely vulnerable against attack and provided a poor and unstrategic defense.
The British proved torpedoes, modified for shallow water, could be effective in their attack on the Regia Marina
Regia Marina
The Regia Marina dates from the proclamation of the Kingdom of Italy in 1861 after Italian unification...
at Taranto
Battle of Taranto
The naval Battle of Taranto took place on the night of 11–12 November 1940 during the Second World War. The Royal Navy launched the first all-aircraft ship-to-ship naval attack in history, flying a small number of obsolescent biplane torpedo bombers from an aircraft carrier in the Mediterranean Sea...
on November 11, 1940. The U.S. Navy discussed this new development as can be seen in a June 1941 memo, as Taranto was about 75 ft (22.9 m) deep and Pearl less than 40 ft (12.2 m). The British attack method was not considered relevant to a torpedo attack at Pearl.
The Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
had used Swordfish
Fairey Swordfish
The Fairey Swordfish was a torpedo bomber built by the Fairey Aviation Company and used by the Fleet Air Arm of the Royal Navy during the Second World War...
torpedo planes, and their low speed was part of the reason the Taranto attack succeeded. The Imperial Japanese Navy
Imperial Japanese Navy
The Imperial Japanese Navy was the navy of the Empire of Japan from 1869 until 1947, when it was dissolved following Japan's constitutional renunciation of the use of force as a means of settling international disputes...
no longer had any similar planes, so they had to develop other methods, both hardware and delivery technique. They independently developed shallow water torpedo modifications (called "Thunder Fish") during the planning and training for the attack in 1941. Wooden fins were added to the tail and anti-roll "flippers" kept the torpedo upright once in the water. The fins kept the torpedo's nose level in the air and broke off on entering the water. The flatter "flight" trajectory helped keep them from diving so deeply as to encounter bottom mud. (Despite these modifications, some Japanese torpedoes did indeed reach the bottom and several remain unaccounted for.) These simple modifications were not anticipated by the USN, and Admiral Bloch (commander of the Pearl Harbor Naval District) did not push to install torpedo nets
Torpedo nets
Torpedo nets were a passive naval warship defensive device against torpedoes. Their use was common practice from the 1890s through World War II...
or baffles at Pearl. Nor, it seems, did anyone else. Practical considerations also were an influence. Due to the shallow anchorage (which continues to require regular dredging), installation of torpedo nets would have severely restricted the mobility of vessels in the harbor.
Kimmel and his staff testified regarding torpedo nets and booms: "(m) Fact XV ... The decision not to install baffles appears to have been made by the Navy Department." That is, in Washington, DC, rather than in Hawaii.
Role of American carriers
None of the three U.S. Pacific Fleet aircraft carriers were in Pearl Harbor when the attack came. This has been alleged by some to be evidence of advance knowledge of the attack by those in charge of their disposition; the carriers were supposedly away so as to save them (the most valuable ships) from attack.In fact, the two carriers then operating with the Pacific Fleet, Enterprise and Lexington, were on missions to deliver fighters to Wake and Midway Islands, which were intended in part to protect the route used by planes (including B-17s) bound for the Philippines. (The third, Saratoga, was in routine refit
REFIt
rEFIt is a boot menu and maintenance toolkit for EFI-based machines like the Intel Macs. It can be used to boot multiple operating systems, including triple-boot setups with Boot Camp. It also provides a way to enter and explore the EFI pre-boot environment. The name "rEFIt" is likely a play on the...
in Puget Sound
Puget Sound
Puget Sound is a sound in the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins, with one major and one minor connection to the Strait of Juan de Fuca and the Pacific Ocean — Admiralty Inlet being the major connection and...
, at the Bremerton shipyard.) At the time of the attack, Enterprise was about 200 mi (173.8 nmi; 321.9 km) west of Pearl Harbor, heading back. In fact, Enterprise had been scheduled to be back on December 6, but was delayed by weather. A new arrival estimate put her arrival at Pearl around 07:00, almost an hour before the attack, but she was also unable to make this schedule.
Furthermore, at the time, aircraft carriers were classified as fleet scouting elements, and hence relatively expendable. They were not capital ship
Capital ship
The capital ships of a navy are its most important warships; they generally possess the heaviest firepower and armor and are traditionally much larger than other naval vessels...
s. The most important vessels in naval planning even as late as Pearl Harbor were battleships (per the Mahan doctrine
Doctrine
Doctrine is a codification of beliefs or a body of teachings or instructions, taught principles or positions, as the body of teachings in a branch of knowledge or belief system...
followed by both the U.S. and Japanese navies at the time). Carriers became the Navy's most important ships only following the attack.
At the time, naval establishments all over the world regarded battleships, not carriers, as the most powerful and significant elements of naval power. Had the U.S. wanted to preserve its key assets from attack, it would almost certainly have focused on protecting battleships. It was the attack on Pearl Harbor itself that first helped vault the carrier ahead of the battleship in importance. The attack demonstated the carrier's unprecedented ability to attack the enemy at a great distance, with great force and surprise. The U.S. would turn this ability against Japan. Elimination of battleships from the Pacific Fleet forced the Americans to rely on carriers for offensive operations. To posit the preservation of the carriers as proof or evidence of advance knowledge of the attack is untenable.
American response to attack
Closer to the moment of the attack, the attacking planes were detected and tracked as they approached by an Army radar installation being operated that morning as a mostly unofficial training exercise. The Opana Point radar station, operated by two enlisted men (Pvts. Lockard and Elliot) plotted the approaching force, and their relief team plotted them returning to the carriers. Elliott called in the reading to the information center. The call was received by Pvt. Joseph McDonald. McDonald found Lt Kermit A. Tyler, the junior officer in charge at the barely operational warning information center at Pearl Harbor, and indicated that a large number of planes were coming in from the north and that he never received a call like this before. Tyler told McDonald that it's nothing.McDonald called back the Opana radar when he reached Pvt. Joseph Lockard. Lockard told McDonald that the radar return was the largest that he had ever seen. McDonald insisted that Tyler speak directly to Lockard. Lockard was told "Well don't worry about it." McDonald asked Tyler if he should call back the plotters and warn Wheeler Field. Tyler indicated that it was not necessary.
The initial radar returns were thought by the ill-trained junior officer to be a flight of American bombers expected from the mainland. In fact those bombers did arrive, from a somewhat different bearing in the middle of the attack. Additionally, Japanese submarines were sighted and attacked (by the destroyer ) outside the harbor entrance a few hours before the attack commenced, and at least one was sunk—all before the planes came within even radar range. This might have provided enough notice to disperse aircraft and fly off reconnaissance, except, yet again, reactions of the duty officers were tardy. It has been argued that failure to follow up on DF bearings saved . If she had been correctly directed, she might have run into the six carrier Japanese strike force.
After the attack, the search for the attack force was concentrated south of Pearl Harbor, continuing the confusion and ineffectiveness of the American response.
Roosevelt's desire for war with Germany
An attack by Japan on the U.S. could not guarantee the U.S. would declare war on Germany. After such an attack, American public anger would be directed at Japan, not Germany, just as happened. The Tripartite Pact (Germany, Italy, Japan) called for each to aid another in defense; Japan could not reasonably claim America had attacked Japan if she struck first. For instance, Germany had been at war with the UK since 1939, and with the USSR since June 1941, without Japanese assistance. There had been a serious, if low-level, naval war going on in the Atlantic between Germany and the U.S. since summer of 1941, as well. Nevertheless, it was only Hitler's declaration of war on 11 December, unforced by treaty, that brought the U.S. into the European war.
Clausen and Lee's Pearl Harbor: Final Judgement contains some interesting information on the intelligence available to Roosevelt and Churchill prior to the attack. On page 367 in the Appendix is a Purple message, dated 29 November 1941, from the Japanese Ambassador in Berlin to Tokyo. A closing paragraph reads, "... He (Ribbentrop) also said that if Japan were to go to war with America, Germany would, of course, join in immediately, and Hitler's intention was that there should be absolutely no question of Germany making a separate peace with England. ..." According to David Irving
David Irving
David John Cawdell Irving is an English writer,best known for his denial of the Holocaust, who specialises in the military and political history of World War II, with a focus on Nazi Germany...
, Churchill (having full access to Purple traffic) was well aware of this message, noting it in red ink. While theorists challenging the conventional view the attack was a surprise treat this as a guarantee to join after Japan's attack, it can as easily be taken as a guarantee to come to Japan's aid, as Germany had done for Italy in Libya
Libya
Libya is an African country in the Maghreb region of North Africa bordered by the Mediterranean Sea to the north, Egypt to the east, Sudan to the southeast, Chad and Niger to the south, and Algeria and Tunisia to the west....
.
Release of information – delays and problems with declassification
Conflicting stories regarding FOIA (Freedom of Information Act) requests for the source materials used, e.g., Sheet Number 94644, or materials available at the National Archives are also common among the debate. However, much information has been said to have been automatically destroyed under a destruction of classified information policy during the war itself. Note various authors have nevertheless continued to bring classified Pearl Harbor materials to light via FOIA.For instance, Sheet No. 94644 derives from its reference in the FOIA-released Japanese Navy Movement Reports of Station H in November 1941. Entries for 28 November 1941 have several more items of interest, each being a "movement code" message (indicating ship movements or movement orders), with specific details given by associated Sheet Numbers. Examples are: Sheet No. 94069 has information on "KASUGA MARU" - this being hand-written (Kasuga Maru was later converted to CVE Taiyo
Japanese aircraft carrier Taiyo
Taiyō was the lead ship of Taiyō-class of escort carrier operated by the Imperial Japanese Navy in World War II.-Construction and Conversion:...
); Sheet No. 94630 is associated with IJN oiler Shiriya (detailed to the Midway Neutralization Force, with destroyers Ushio and Sazanami, not the Kido Butai); and finally for Sheet No. 94644 there is another hand-written remark "FAF using Akagi xtmr" (First Air Fleet using Akagis transmitter). It is known the movement reports were largely readable at the time.
These three documents (Sheet Numbers 94069, 94630, and 94644) are examples of materials which yet, even after decades and numerous specific FOIA requests, have not been declassified fully and made available to the public. Sheet Number 94644, for example, noted as coming from Akagis transmitter and as being a "movement code" report, would have likely contained a reported position.
Another issue in the debate is the fact neither Admiral Kimmel nor General Short ever faced court martial. It is alleged this was to avoid disclosing information showing the U.S. had advanced knowledge of the attack. When asked, "Will historians know more later?", Kimmel replied, "' ... I'll tell you what I believe. I think that most of the incriminating records have been destroyed. ... I doubt if the truth will ever emerge.' ..." From Vice Admiral Libby, "I will go to my grave convinced that FDR ordered Pearl Harbor to let happen.
He must have known." It is equally likely this was done to avoid disclosing the fact Japanese codes were being read, given there was a war on.
Unreleased classified information
Part of the controversy of the debate centers on the state of documents pertaining to the attack. There are some related to Pearl Harbor which have not been made public. Some may no longer exist, as many documents were destroyed early during the war due to fears of an impending Japanese invasion of Hawaii. Still others are partial and mutilated. A purported transcript of a conversation between Roosevelt and Churchill in late November 1941 was analyzed and determined to be fake. There are claims about these conversations; much of this is based on fictional documents, often cited as "Roll T-175" at the National Archives. There is no Roll T-175; NARA does not use that terminology.External links
- PEARL HARBOR: HENRY STIMSON'S VIEW Time Magazine Monday, Apr. 01, 1946
- Did Roosevelt know in advance about the attack on Pearl Harbor yet say nothing? – The Straight Dope, Straight Dope Science Advisory Board, February 28, 2001
- The Independent Institute: Pearl Harbor Archive – Mostly a Stinnett site, but also has Pearl Harbor articles, debates, interviews, transcripts, book reviews, books, and Pearl Harbor documents
- The National Defense Authorization Act (where it is noted that available intelligence regarding an impending attack was not conveyed to the American commanders at Pearl Harbor; page 121, section 546).
- Closing the Book on Pearl Harbor – Stephen Budiansky on OP-20-G's progress breaking JN-25 from its appearance in 1939 to 12.7.41. In part a response to Stinnett's (and others') claims of major JN-25 breaks prior to the Attack.
- Communism at Pearl Harbor – An article proposing that the Russians maneuvered the U.S. into war
- An Interview with Robert Stinnett and WWII Vet O'Kelly McCluskey.
- Foreknowledge of Pearl Harbor? No!: The story of the U. S. Navy's efforts on JN-25B – Excellent in depth article illustrating the problems with Stinnett and Wilford's claims regarding JN-25.
- Rebuttal of Robert Stinnett's "Day of Deceit" with extensive, updated citations by Rear Admiral Richard E. Young, USN (Ret)
- The Myths of Pearl Harbor – Extensive site debunking claims of advance knowledge of the attack.
- The Great Pacific War – 16 years before Pearl Harbor attack, an English naval writer Hector Charles BywaterHector Charles BywaterHector Charles Bywater was a British journalist and military writer.H.C. Bywater was the second son of a middle class Welshman. The family had emigrated into the United States in 1901...
uncannily prophesied in detail the war in the Pacific. - Pearl Harbor In the Wake of the Prophet – It prophesied the Pacific War in detail.
- Freedom Daily. Sheldon Richman. December 1991. Pearl Harbor: The Controversy Continues Article on foreknowledge as well as steps that might have provoked Japan