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Trident: The US connection


Trident is a US nuclear system. The US provides assistance to Britain with its nuclear programme under the 1958 US-UK Mutual Defence Agreement.

  • The UK Trident uses US Trident II D5 missiles, which are maintained and tested in the United States.
  • The UK Trident warhead is closely based on the US Trident W76 warhead and was tested at the US Nevada Test Site.
  • The UK maintains close links with the US nuclear weapons laboratories, on "stockpile stewardship", ie maintaining and developing nuclear warheads.
  • The UK relies on US satellite navigation, intelligence and targetting information
  • UK nuclear policy is closely synchronised with the US and NATO.

Although the Government claims that Trident is "independent", it is clear that the UK depends heavily on the US for nuclear assistance and that the US therefore has leverage over British foreign and defence policy.

Trident missiles

The UK has access to 58 missiles from the US pool of Trident II D5 missiles. British Trident Submarines collect the missiles from the US Trident base at Kings Bay, Georgia in the South-East of the United States. While the submarines are in the United States, they will usually test fire one or two missiles at the US Eastern Test Range, off the coast of Florida, where the US test fires its Trident missiles. The Trident missiles are maintained and serviced in the United States.

Trident warheads

The UK Trident warhead is closely based on the US Trident W76 warhead and was tested underground at the US nuclear test site in Nevada.

The UK works closely on design and maintenance of its nuclear warheads with the 3 main US nuclear weapons laboratories, Lawrence Livermore in California and Los Alamos and Sandia in New Mexico. Components for British nuclear weapons are transported by air and road between AWE Aldermaston and RAF Brize Norton in the UK and the US weapons laboratories for ongoing tests.

The UK participates in numerous exchange visits with staff from the US nuclear weapons laboratories. It also participates with the US in "sub-critical" nuclear tests (tests which fall just short of releasing a nuclear explosion) at the Test Site.

Cooperation on Nuclear Posture

Under the terms of the agreement under which the US provided assistance with Trident to the UK, UK Trident submarines are assigned to NATO to be used for the "defence of the Alliance" except where the UK government "may decide that supreme national interests are at stake".

UK nuclear strategy and targeting is closely coordinated with the US through the NATO Nuclear Planning Group. NATO's nuclear posture, which is heavily influenced by the United States includes the option of using nuclear weapons first and the option to use nuclear weapons against non-nuclear countries.

As the Bush administration has moved towards a more aggressive nuclear posture, the UK and NATO are expected to fall into line. British Secretary of State for Defence Geoff Hoon MP has already indicated that like the US, the UK reserves “the right to use appropriate proportionate responses which might… in extreme circumstances include the use of nuclear weapons.” (Defence Select Committee 20 March 2002, See Question 234.