The Warsaw Treaty of Friendship Cooperation and Mutual Assistance was signed in 1955 by Albania, Bulgaria, Czechoslovakia, German Democratic Republic (East Germany), Hungary, Poland, Romania and the Soviet Union. The Warsaw Pact was created in response to the decision to allow the Federal Republic of Germany (West Germany) to join the North Atlantic Treaty Organization (NATO).

The Warsaw Pact allowed for the Red Army to be based in member states. It also provided for a unified military command and a system of mutual assistance. This enabled the Soviet Union to launch a multinational invasion of Czechoslovakia in 1968.