Warsaw Pact
Also: Warsaw Treaty Organization, Treaty of Friendship, Cooperation and Mutual Assistance
Background and evolution
After the Second World War, the Soviet Union established communist governments across Eastern Europe. The United States and Western European countries formed NATO in 1949. When West Germany was rearmed and admitted to NATO in May 1955, the Soviet Union responded within days by creating a formal alliance of its own. It also had political value: it gave legal cover for Soviet troops stationed in member states.
The Pact was used less against the West than to keep members in line. In 1956, Soviet forces crushed the Hungarian uprising after Hungary announced it would leave the Pact. In 1968, troops from the USSR, Poland, Hungary and Bulgaria invaded Czechoslovakia to end the "Prague Spring" reforms of Alexander Dubček. The Soviet justification, called the Brezhnev Doctrine, claimed the right to intervene when socialism was threatened in any member.
In the late 1980s, Mikhail Gorbachev's reforms (glasnost and perestroika) and his decision not to use force in Eastern Europe allowed the revolutions of 1989. The Berlin Wall fell, Germany was reunited in 1990 within NATO, and the Pact was formally ended in 1991.
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Last reviewed: 23 October 2026 · Original UPSCPrep.in content.