British timing was good . The Soviet Union 's launch of Sputnik 1 , the world 's first artificial satellite , on 4 October 1957 , came as a tremendous shock to the American public , who had trusted that American technological superiority ensured their invulnerability . Now , suddenly , there was incontrovertible proof that , in some areas at least , the Soviet Union was actually ahead . In the widespread calls for action in response to the Sputnik crisis , officials in the United States and Britain seized an opportunity to mend the relationship with Britain that had been damaged by the Suez Crisis the year before . At the suggestion of Harold Caccia , the British Ambassador to the United States , Macmillan wrote to Eisenhower on 10 October urging that the two countries pool their resources , as Macmillan put it , " to meet the Soviet challenge on every front , military , political , economic and ideological . " Macmillan flew to Washington , DC , for talks on 25 October , despite concerns that the 10 October Windscale fire might prove a stumbling block in negotiations . He immediately sensed how shaken the Americans had been by Sputnik . It placed the Eisenhower administration under great public pressure to act on the deployment of IRBMs by a shocked and distraught nation . Eisenhower and Macmillan agreed to form a study group headed by Sir Richard Powell , the Permanent Secretary to the Ministry of Defence , and Donald A. Quarles , the United States Deputy Secretary of Defense , to consider how the deployment of IRBMs to Britain might be expedited . Another study group , under Strauss and Sir Edwin Plowden , the head of the United Kingdom Atomic Energy Authority ( UKAEA ) , would investigate nuclear co-operation and the exchange of nuclear information . The personal relationship developed between Plowden and Strauss would be crucial in converting the latter over to the idea of providing information to Britain
Windscale fire
Windscale fire
1958 US–UK Mutual Defence Agreement