In 1968 reform-minded elements of the Communist Party of Czechoslovakia rapidly began to liberalize their rule, loosen censorship, and strengthen Western ties. In response, Soviet and other [[Warsaw Pact]] troops entered Czechoslovakia and installed a new regime. Out of these events arose the so-called Brezhnev Doctrine, which warned that the Soviet Union would act to maintain its hegemony in Eastern Europe. Soviet suppression of the reform movement reduced blatant gestures of defiance on the part of Romania and served as a threatening example to the Polish Solidarity trade union movement in 1980. But it also helped disillusion communist parties in Western Europe to the extent that by 1977 most of the leading parties embraced Eurocommunism, which freed them to pursue political programs independent of Moscow's dictates.