British Trident system

The Trident nuclear programme, also known as the Trident nuclear deterrent, covers the development, procurement and operation of the current generation of United Kingdom nuclear weapons and the means to deliver them.

'Trident' is an operational system of four Vanguard-class submarines armed with Trident II D-5 ballistic missiles, able to deliver thermonuclear warheads from multiple independently-targetable re-entry vehicles (MIRVs). It is operated by the Royal Navy and based at Clyde Naval Base on the west coast of Scotland, 25 miles from Glasgow—Scotland's largest city and the UK's third largest city. At least one submarine is always on patrol to provide a continuous at-sea capability. Each one is armed with up to 8 missiles and 40 warheads; their capacity is much larger.

The programme was announced in July 1980 and patrols began in December 1994. Since tactical WE.177 free-fall bombs were decommissioned in 1998, 'Trident' has been the only nuclear weapon system that is operated by the UK. Its stated purpose by the Ministry of Defence is to "deter the most extreme threats to our national security and way of life, which cannot be done by other means". Trident replaced the submarine-based Polaris system, in operation from 1968 until 1996.

A programme for the replacement of the Vanguard-class is under way. On 18 July 2016 the House of Commons voted by a large majority to proceed with building a fleet of Dreadnought-class submarines, to be operational by 2028 (with the current fleet completely phased out by 2032) thereby renewing the Trident system and extending its life until the 2060s.

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