Yet all the while Britain strove for independence , at the same time it sought interdependence in the form of a renewal of the Special Relationship with the United States . This was desired more than ever , as other countries recovered from the war and once again began to challenge Britain 's status . As successful as it was , High Explosive Research fell short on both counts . The technology demonstrated at Monte Bello in October 1952 was already seven years old . The following month the United States tested Ivy Mike , a thermonuclear device . The British government would now have to decide whether to initiate its own hydrogen bomb programme . Penney , for one , feared that this would likely prove to be beyond the financial resources of Britain 's war-ravaged economy . The successful British hydrogen bomb programme , and a favourable international relations climate caused by the Sputnik crisis , led to amendment of the United States Atomic Energy Act in 1958 , and a resumption of the nuclear Special Relationship between America and Britain under the 1958 US – UK Mutual Defence Agreement
Ivy Mike
Ivy Mike
High Explosive Research