The era from 1946 to 1990 is known as the Cold War, during which the U. countries attempted to contain the rapid spread of communism by the Warsaw Pact nations, including the Soviet Union. The Warsaw Pact played a major part in the Soviet Union's plan to spread communism through the Eastern European countries and then throughout the west. The Warsaw Pact is, overlooked part of the Cold War, was a key factor in the communist countries and in relations to N.A.T.O.
During World War Two, the Soviet Union's Red Army liberated Eastern Europe from Nazi Germany control. The Red Army liberated Bulgaria, Hungary, Romania, Poland, and Czechoslovakia. So, by the end of World War Two, all of these countries, including East Germany were under Soviet control. The Red Army also combined with the armies of the liberated countries, creating a force consisting of 500,000 troops. After the war ended, tensions grew between the Soviet Union and its former World War Two allies. France, Great Britain, and the U.S. disagreed with the Soviets on topics such as the division of Germany, free elections in Poland, and the reparations paid by Germany. These disagreements caused a separation between the Soviet Union and its former Allies (Appendix C: The Warsaw Pact, online).
In 1955, the Soviet Union, in direct response to the addition of West Germany into N.A.T.O., formed the Warsaw Pact with Albania, Bulgaria, Czechoslovakia, Hungary, Poland, and Romania (The Western Alliance, 20). The Warsaw Pact acted as a counter weight to the noncommunist N.A.T.O. countries. The Warsaw Pact's duration was set at 20 years and then a 10 year extension if there was no disapproval of it before it expired. The Warsaw Pact was a treaty of friendship, cooperation, and mutual assistance in a time of need. It was not created for the sole purpose of making every country in Europe Communist. In 1956, Nikita S. Khrushchev changed the amount of Soviet control of the Warsaw Pact by removing Soviet forces from the other countries in the Warsaw Pact.