The Trident missile is a submarine-launched ballistic missile (SLBM) designed by Lockheed Martin Space Systems in the United States which is armed with nuclear warheads and is launched from SSBNs, nuclear-powered ballistic missile submarines.

Trident missiles are carried by fourteen active US Navy Ohio class submarines and, with British warheads, four Royal Navy Vanguard class submarines.
 

The UK Strategic deterrent (US Trident D-5) is deployed in the four Vanguard class Ballistic Missile Nuclear-Powered Submarines (SSBNs). The Trident D-5 missile is a three-stage, solid propellant Submarine Launched Ballistic Missile (SLBM) - it is 13.42 m long and has a body diameter of 2.11 m.

It has a launch weight of 59,090 kg and a maximum range of 12,000 km. The minimum range is believed to be about 2,500 km.

It has been stated that the UK missiles will carry up to eight warheads each, but it is expected that there will be between one and four warheads fitted to most missiles. The UK plans to use some Trident D-5 missiles in a `sub-strategic' role, with a single warhead set to produce a smaller yield, believed to be around 10 kT.