The formation of the Warsaw Pact was in some ways a response to the creation of NATO, although it did not occur until six years after the Western alliance came into being. It was more directly inspired by the rearming of West Germany and its admission into NATO in 1955. In the aftermath of World War I and World War II, Soviet leaders felt very apprehensive about Germany once again becoming a military power–a concern that was shared by many European nations on both sides of the Cold War divide.
In the mid-1950s, however, the U.S. and a number of other NATO members began to advocate making West Germany part of the alliance and allowing it to form an army under tight restrictions. The Soviets warned that such a provocative action would force them to make new security arrangements in their own sphere of influence, and they were true to their word. West Germany formally joined NATO on May 5, 1955, and the Warsaw Pact was signed less than two weeks later, on May 14. Joining the USSR in the alliance were Albania, Bulgaria, Czechoslovakia, the German Democratic Republic (East Germany), Hungary, Poland and Romania. This lineup remained constant until the Cold War ended with the dismantling of all the Communist governments in Eastern Europe in 1989 and 1990.
Like NATO, the Warsaw Pact focused on the objective of creating a coordinated defense among its member nations in order to deter an enemy attack. There was also an internal security component to the agreement that proved useful to the USSR. The alliance provided a mechanism for the Soviets to exercise even tighter control over the other Communist states in Eastern Europe and deter pact members from seeking greater autonomy. When Soviet leaders found it necessary to use military force to put down revolts in Hungary in 1956 and in Czechoslovakia in 1968, for example, they presented the action as being carried out by the Warsaw Pact rather than by the USSR alone.