Abstract
Contrary to some interpreters of the Berlin Crisis 1958-61, documents from the archives of the Czechoslovak Communist Party show the most important factor for Moscow to have been the behaviour of the United States rather than pressure from the East German Communist leader Walter Ulbricht. After Khrushchev first overestimated the willingness of President Eisenhower to reach a compromise, in the aftermath of the US fiasko at the Bay of Pigs he believed that President Kennedy would not risk a war over West Berlin. The Vienna summit provided Khrushchev with an opportunity to intimidate the young president and prepare the ground for unilateral changes in Berlin. Thanks only to strong US policy in the summer of 1961 did the Soviet leader change his mind and content himself with halting East German immigration through the wall.