The Polaris Sales Agreement was a treaty between the United States and the United Kingdom which began the UK Polaris programme. The agreement was signed on 6 April 1963. It formally arranged the terms and conditions under which the Polaris missile system was provided to the United Kingdom. The United Kingdom had been planning to buy the air-launched Skybolt missile to extend the operational life of the British V bombers, but the United States decided to cancel the Skybolt program in 1962 as it no longer needed the missile. The crisis created by the cancellation prompted an emergency meeting between the President of the United States, John F. Kennedy, and the Prime Minister of the United Kingdom, Harold Macmillan, which resulted in the Nassau Agreement, under which the United States agreed to provide Polaris missiles to the United Kingdom instead. The Polaris Sales Agreement provided for the implementation of the Nassau Agreement. The United States would supply the United Kingdom with Polaris missiles, launch tubes, and the fire control system. The United Kingdom would manufacture the warheads and submarines. In return, the US was given certain assurances by the United Kingdom regarding the use of the missile, but not a veto on the use of British nuclear weapons. The British Polaris ballistic missile submarines were built on time and under budget, and came to be seen as a credible deterrent. Along with the 1958 US–UK Mutual Defence Agreement, the Polaris Sales Agreement became a pillar of the nuclear Special Relationship between Britain and the United States. The agreement was amended in 1982 to provide for the sale of the Trident missile system. Background During the early part of the Second World War, Britain had a nuclear weapons project, codenamed Tube Alloys. In August 1943, the Prime Minister of the United Kingdom, Winston Churchill and the President of the United States, Franklin Roosevelt, signed the Quebec Agreement, which merged Tube Alloys with the American Manhattan Project. The British government trusted that the United States would continue to share nuclear technology, which it regarded as a joint discovery, but the 1946 McMahon Act ended cooperation. Fearing a resurgence of United States isolationism, and Britain losing its great power status, the British government restarted its own development effort, now codenamed High Explosive Research. The first British atomic bomb was tested in Operation Hurricane on 3 October 1952. The subsequent British development of the