What was the name of the Soviet military alliance formed in 1955?

The Soviet military alliance formed in 1955 was the Warsaw Pact. Formally called the Treaty of Friendship, Cooperation and Mutual Assistance, it was signed in Warsaw on 14 May 1955 by the Soviet Union and seven Eastern European countries.

The alliance was created soon after West Germany joined NATO. Soviet leaders presented it as a collective-security response to the remilitarization and Western alignment of West Germany, though the USSR already dominated the military and political affairs of most prospective members. The pact provided a formal framework for coordinating their armed forces under Soviet leadership.

Its members initially included Albania, Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, Romania, and the Soviet Union. The organization was used to maintain the Eastern Bloc, including during the 1968 invasion of Czechoslovakia. It was not the same as NATO: NATO was the Western alliance, while the Warsaw Pact was its principal Eastern Bloc counterpart. The pact was dissolved in 1991.