Dan Plesch: Britain's independent deterrent is purely a political myth

In 1962 the US Defence Secretary Robert McNamara revealed that the British force "did not operate independently" to Harold Macmillan's embarrassment. When Macmillan later accepted President John Kennedy's offer of the Polaris missile submarine, his Permanent Secretary, Sir Robert Scott, recorded that the decision has "put us in America's pocket for a decade". Sir John Slessor, the commander of the V bomber force, wrote privately that the deal had been done to sustain the "myth" of an independent force. President Charles De Gaulle of France turned down the same offer and built an independent force de frappe. De Gaulle then vetoed UK membership of the Common Market on the grounds that the Polaris deal had made Britain an American vassal.

Former naval officers have confirmed privately that the US knows where the British submarines are and that firing the missiles without US supplied data and satellites is almost impossible. Although a British prime minister could theoretically fire the weapons, a US president would have the full range of political and military options to prevent Britain engaging in a nuclear war against Washington's wishes.

In any longer-term disagreement between London and Washington, the US can remove the illusion of Britain's nuclear status. One former Royal Navy officer who conducted an official study of the dependence on the US concluded that in just 18 months after a US decision to withdraw support, the UK could no longer send Trident to sea.

The Atomic Weapons Establishment at Aldermaston outside Reading is one-third managed by the US firm Lockheed Martin. The British Government refuses to say how much of the AWE budget goes to US firms. Research by non-government groups, including Basic, Greenpeace and NRDC, show that the nuclear warhead factory was designed and built by a US company as a copy of the one at Los Alamos. The British fuse and firing system is designed and built by America's Sandia national laboratory. Some of the nuclear explosive are imported from the US and so too is the warhead casing and guidance system. The US has been providing Britain with the blueprints of nuclear weapons for more than 40 years.

President George Bush agreed last year to renew the Mutual Defence Agreement providing nuclear support to the UK until 2014, stating that "in the light of our previous close co-operation, I have concluded that it is in our interest to continue to assist them in maintaining a credible nuclear force". Without Bush's support, the British nuclear force would not be credible and without close co-operation with Washington that credibility will not be sustained. South Africa and the developing world charge that the indirect supply of nuclear weapons to Britain under this agreement is a violation of the Non-Proliferation Treaty, which bans such transfers.

This myth of the independent nuclear force is the last taboo of British politics. British politicians and civil servants are prepared to tie the UK to US policy as the price of being able to pretend to have the status of an independent nuclear power.

The real question for the country is not whether to renew the independent deterrent but whether it wants to be independent of the US, for a successor to Trident will be with us until 2060.

Dan Plesch's report on the Trident successor will be published next month by the Foreign Policy Centre, where he is a senior associate