Trident (UK nuclear programme) Agreement merged with the American Manhattan Project to create a combined American, British, and Canadian project. The British government expected that the United States would continue to share nuclear technology, which it regarded as a joint discovery, but the United States Atomic Energy Act of 1946 (McMahon Act) ended technical co-operation. Fearing a resurgence of United States isolationism, and Britain losing its great power status, the British government resumed its own development effort. The first British atomic bomb was tested in Operation Hurricane on 3 October 1952. The subsequent British development of the hydrogen bomb, and a fortuitous international relations
History of the Teller–Ulam design "secret"), the United States agreed to exchange some of its nuclear designs with Great Britain, leading to the 1958 US-UK Mutual Defence Agreement. The People's Republic of China detonated its first device using a Teller–Ulam design June 1967 ("Test No. 6"), a mere 32 months after detonating its first fission weapon (the shortest fission-to-fusion development yet known), with a yield of 3.3 Mt. Little is known about the Chinese thermonuclear program, however. Very little is known about the French development of the Teller–Ulam design beyond the fact that they detonated a 2.6 Mt device in the "Canopus" test in August