After World War Two a Cold War developed between the capitalist Western countries and the Communist countries of the Eastern Bloc. Soviet leader Joseph Stalin wanted a buffer zone of friendly Communist countries to protect the USSR from further attack in the future.
However, British Prime Minister Clement Attlee and US President Harry Trueman made it clear at Yalta and Potsdam that this was unacceptable to the Western governments. They wanted freely defined states. Communist parties had gained control through what the Hungarian leader, Rakosi, called
By 1950, the Eastern Bloc consisted of many Eastern European countries which were under the influence of the USSR. These included Poland, Hungary, Czechoslovakia and Ukraine.
After Stalin's death in 1953, there was a power struggle in the USSR. By the mid-1950s the dominant Soviet political figure Nikita Khrushchev was solidifying his grasp on power.
In 1956, he made a speech to the Twentieth Communist Party Congress highlighting his desire for a relaxation of controls that had been present under Stalin. This caused widespread unrest across Europe.