The Trident missile is a submarine-launched ballistic missile

Submarine-launched ballistic missile

A submarine-launched ballistic missile is a ballistic missile capable of delivering a nuclear warhead that can be launched from submarines. Modern variants usually deliver multiple independently targetable reentry vehicles each of which carries a warhead and allows a single launched missile to...

 (SLBM) equipped with multiple independently-targetable reentry vehicles (MIRV). The Fleet Ballistic Missile (FBM) is armed with nuclear warhead

Nuclear weapon

A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...

s and is launched from nuclear-powered ballistic missile submarine

Ballistic missile submarine

A ballistic missile submarine is a submarine equipped to launch ballistic missiles .-Description:Ballistic missile submarines are larger than any other type of submarine, in order to accommodate SLBMs such as the Russian R-29 or the American Trident...

s (SSBNs). Trident missiles are carried by fourteen active US Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 Ohio class submarine

Ohio class submarine

The Ohio class is a class of nuclear-powered submarines used by the United States Navy. The United States has 18 Ohio-class submarines:...

s, with U.S. warheads, and four 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...

 Vanguard class submarine

Vanguard class submarine

The Vanguard class are the Royal Navy's current nuclear ballistic missile submarines , each armed with up to 16 Trident II Submarine-launched ballistic missiles...

s, with British warheads. The original prime contractor and developer of the missile was Lockheed Martin Space Systems

Lockheed Martin Space Systems

Lockheed Martin Space Systems Company is one of the four major business divisions of Lockheed Martin. It is headquartered in Denver, Colorado with additional sites in Sunnyvale, California; Newtown, Pennsylvania; Huntsville, Alabama; and elsewhere in the US and UK...

.
Trident I (designated C4) was deployed in 1979 and phased out in the 1990s and early 2000s.