Prague Spring
The Prague Spring refers to a period of political liberalization in Czechoslovakia during the year of 1968, up to the point when the USSR and its Warsaw Pact allies invaded it on August 20 of that year. The Czechs had shown increasing signs of independence under the leadership of Alexander Dubcek. Dubcek's reforms of the political process inside Czechoslovakia, which he refered to as "Socialism with a human face", did not represent a complete overthrow of the old regime, as was the case in Hungary in 1956. However, it was still seen by the Soviet leadership as a threat to their hegemony over other Eastern European states shackled beneath the yoke of the Comintern. The policy of the USSR to enforce Soviet-style governments among its satellite states, through military invasion if necessary, became known as the "Brezhnev Doctrine", named after the Soviet leader, Leonid Brezhnev. This doctrine held in force until it was replaced by the Sinatra Doctrine under Mikhail Gorbachev in the 1980s.