During the immediate postwar period, the Soviet Union first rebuilt and then expanded its economy, while maintaining centralization of communism. The Soviet Union aided post-war reconstruction in the countries of Eastern Europe while turning them into Soviet satellite states and founded the Warsaw Pact in 1955. Later, the Comecon supplied aid to the eventually victorious Communists in the People's Republic of China, and saw its influence grow elsewhere in the world. Amongst these successes, there were still political upheavals occurring during the reign of Stalin and Khrushchev, therefore leading to some significant, withstanding changes in Eastern Europe.
Mindful of the numerous invasions of Russia and the Soviet Union from the West throughout history, Stalin sought to create a buffer zone of subservient East European countries, most of which the Red Army (known as the Soviet army after 1946) had occupied in the course of the war. Taking advantage of its military occupation of these countries, the Soviet Union actively assisted local communist parties in coming to power. In 1946, besides an anti-intellectual campaign against literary and scientific works, a new political terror had begun. In 1953, a number of Jewish doctors were implicated in a plot to kill high level party officials. However, Stalin’s death on March 5, 1953 prevented more bloodletting. For 15 years, Stalin had been able to remove any, if not all, opposition to his rule, even pitting his subordinates against one another for his own benefit.
Soviet relations with the West, especially the United States, seesawed between moments of relative relaxation and periods of tension and crisis. In 1953, Nikita Khrushchev became the first secretary of the Communist Party. Khrushchev wanted peaceful coexistence with the West, not only to avoid nuclear war but also to permit the Soviet Union to develop its economy. He also denounced Stalin for his “Administrative violence, mass repression, and terror”.
To maintain national prestige, Khrushchev canceled a summit meeting with Eisenhower in 1960 after Soviet air defense troops shot down a United States U-2 reconnaissance aircraft over Soviet territory. To offset the United States military advantage and thereby improve the Soviet negotiating position, Khrushchev in 1962 tried to install nuclear missiles in Cuba, but he agreed to withdraw them after Kennedy ordered a blockade around the island nation. This was the last straw. In 1964, the soviet Politboro voted him out of office. Real power came in the form of Leonid Brezhnev, his trusted supporter, who had engineered his downfall.
The Soviet Union initially maintained control behind the "iron curtain" through troops, security police, and its diplomatic service. Unequal trade agreements with the East European countries permitted the Soviet Union access to valued resources. Furthermore, while the Soviet Union gained a new satellite nation in the German Democratic Republic, it lost its influence in Yugoslavia.
The Soviet “sphere of influence”, known as the Warsaw Pact, fell between the Western democratic nations and the nations of Eastern Europe. By ensuring Communist governments were installed in Eastern Europe and, more importantly, by maintaining them through such actions as the Invasion of Hungary and Czechoslovakia, the Soviet Union ensured that the Cold War continued until the fall of the Berlin Wall.