1958 US–UK Mutual Defence Agreement
1958 US–UK Mutual Defence Agreement . The 1958 US–UK Mutual Defence Agreement is a bilateral treaty between the United States and the United Kingdom on nuclear weapons co-operation. It allows the two countries to exchange nuclear materials, technology and information, and was signed on 3 July 1958, after the British hydrogen bomb programme successfully tested a thermonuclear device. While the US has nuclear co-operation agreements with other countries, including France and other NATO countries, this agreement is by far the most comprehensive. Exemplifying the Anglo-American Special Relationship, it allowed American nuclear weapons to be supplied under Project E. The treaty has proved mutually beneficial, and paved the way for the Polaris Sales Agreement and the Trident nuclear programme submarines, including HMS Victorious (pictured), all of which use American missiles with British nuclear warheads. The most recent renewal of the treaty extended it to 31 December 2024.