Nuclear weapon

A nuclear weapon is an explosive device that derives its destructive force from nuclear reaction
Nuclear reaction
In nuclear physics and nuclear chemistry, a nuclear reaction is semantically considered to be the process in which two nuclei, or else a nucleus of an atom and a subatomic particle from outside the atom, collide to produce products different from the initial particles...

s, either fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...

 or a combination of fission and fusion
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...

. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission ("atomic") bomb test released the same amount of energy as approximately 20,000 tons of TNT
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...

. The first thermonuclear ("hydrogen") bomb test released the same amount of energy as approximately 10,000,000 tons of TNT.

A modern thermonuclear weapon weighing little more than 2400 pounds (1,088.6 kg) can produce an explosive force comparable to the detonation of more than 1.2 million tons (1.1 million tonnes) of TNT.

1945    Manhattan Project: the Atomic Age begins when the United States successfully detonates a plutonium-based test nuclear weapon at the Trinity site near Alamogordo, New Mexico.

1945    World War II: Hiroshima is devastated when the atomic bomb "Little Boy" is dropped by the United States B-29 ''Enola Gay''. Around 70,000 people are killed instantly, and some tens of thousands die in subsequent years from burns and radiation poisoning.

1945    World War II: Nagasaki is devastated when an atomic bomb, ''Fat Man'', is dropped by the United States B-29 ''Bockscar''. 39,000 people are killed outright.

1945    The USSR's nuclear program receives plans for the United States plutonium bomb from Klaus Fuchs at the Los Alamos National Laboratory.

1952    The United Kingdom successfully tests a nuclear weapon.

1953    Cold War: U.S. President Dwight D. Eisenhower formally approves the top secret document National Security Council Paper No. 162/2, which states that the United States' arsenal of nuclear weapons must be maintained and expanded to counter the communist threat.

1955    Eighteen Nobel laureates sign the Mainau Declaration against nuclear weapons, later co-signed by thirty-four others.

1962    Cuban Missile Crisis: US President John F. Kennedy, after internal counsel from Dwight D. Eisenhower, announces that American reconnaissance planes have discovered Soviet nuclear weapons in Cuba, and that he has ordered a naval "quarantine" of the Communist nation.

1967    More than sixty nations sign the Outer Space Treaty banning nuclear weapons in space.

1971    Eighty-seven countries, including the US, UK, and USSR, sign the Seabed Treaty outlawing nuclear weapons in international waters.