Trident (UK nuclear programme)

Trident, also known as the Trident nuclear programme or Trident nuclear deterrent, covers the development, procurement and operation of submarine-based nuclear weapons in the United Kingdom. Its purpose, as stated 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 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 reentry vehicles. It is operated by the Royal Navy and based at Clyde Naval Base on the west coast of Scotland. At least one submarine is always on patrol to provide "continuous at-sea deterrence". The missiles are manufactured in the United States, while the warheads are produced by the British Atomic Weapons Establishment. Trident began patrols in 1994, and fully replaced its predecessor, the Polaris submarine fleet, in 1996. The missiles have an intercontinental range of 11,300 kilometres (7,000 mi). Up to 16 missiles can be carried by each submarine, and each missile can carry eight warheads in MIRV configuration. The warheads have a yield of 100 kilotons of TNT, six times greater than the bomb that destroyed Hiroshima. The design, codenamed "Holbrook", is believed to be based on the American W76 warhead used on its own Ohio-class submarines. The programme's acquisition cost was £12.52 billion (approximately £23 billion in 2024/25 prices), and its annual cost is estimated at £3 billion. The submarines' service life was designed to be 25 years but will exceed 36 years. In 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, and to phase out the Vanguard fleet by 2032. A new warhead, Astraea, is also planned to...