The United States terminated co-operation after the war ended with the Atomic Energy Act of 1946 . This prompted the United Kingdom to relaunch its own project , High Explosive Research . Production facilities were established and British scientists continued their work under the auspices of an independent British programme . Finally , in 1952 , Britain performed a nuclear test under codename " Operation Hurricane " . In 1958 , in the wake of the Sputnik crisis and the British demonstration of a two-stage thermonuclear bomb , the United Kingdom and the United States signed US – UK Mutual Defence Agreement , which resulted in a resumption of Britain 's nuclear Special Relationship with the United States
Operation Hurricane
Operation Hurricane
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