The Soviet leader Mikhail Gorbachev replaced the Brezhnev Doctrine with the Sinatra Doctrine in 1988 .
This effectively ment that no country was allowed to leave the Warsaw pact , and the doctrine was used to justify the invasions of Hungary in 1956 , Czechoslovakia in 1968 , and Afghanistan in 1979.In 1988 , Gorbachev officially abandoned the doctrine and replaced it with the
Brezhnev Doctrine