Following the surrender of Nazi Germany in May 1945 near the close of WWII, the uneasy wartime alliance between the United States and Great Britain on the other hand and the Soviet Union on the other began to unravel. By 1948 the Soviets had installed leftwing governments in the countries of Eastern Europe that had been liberated by the Red Army , and the United States and Britain had responded by ending reparations to the Soviet Union from zones of Germany that those two powers occupied.
The Americans and the British feared the permanent Soviet domination of Eastern Europe and the threat of Soviet- influenced communist parties coming to power in the democracies of Western Europe and elsewhere; the Soviets, on the other hand, were determined to maintain control of Eastern Europe in order to safe guard against any possible renewed threat from Germany, and they were intent on spreading communism and the Soviet system worldwide, largely for ideological reasons.
The Cold War had solidified by 1947-48, when U.S. aid provided under Marshall Plan to Western Europe had brought those countries under American influence and the Soviets had installed openly communist regimes in the Eastern European nations that they controlled.
The Cold War reached its peak in 1948-53. In this period the Soviets unsuccessfully blockaded the western-held sectors of West Berlin (1948-49); the United States and its European allies formed the North Atlantic Treaty Organization ( NATO) , a unified military command to resist the Soviet presence in Europe (1949); the Soviets exploded their first