Marxist–Leninists and social democrats. Left communists assert positions which they regard as more authentically Marxist than the views of Marxism–Leninism espoused by the Communist International after its Bolshevization by Joseph Stalin and during its second congress. Libertarian Marxism is a broad scope of economic and political philosophies that emphasize the anti-authoritarian and libertarian aspects of Marxism. End of the Eastern Bloc (1980–1992) Reform and collapse (1980–1992) Social resistance to the policies of communist regimes in Eastern Europe accelerated in strength with the rise of the Solidarity, the first non-communist controlled trade union in the Warsaw Pact that was formed in the People's Republic of Poland in 1980. In 1985, Mikhail Gorbachev rose to power in the Soviet Union and began policies of radical political reform involving political liberalisation called perestroika and glasnost. Gorbachev's policies were designed at dismantling authoritarian elements of the state that were developed by Stalin, aiming for a return to a supposed ideal Leninist state that retained a one-party structure while allowing the democratic election of competing candidates within the party for political office. Gorbachev also aimed to seek détente with the West and end the Cold War that was no longer economically sustainable to be pursued by the Soviet Union. The Soviet Union and the United States under President George H. W. Bush joined in pushing for the dismantlement of apartheid and oversaw the dismantlement of South African colonial rule over Namibia. Meanwhile, the Eastern European communist states politically deteriorated in response to the success of the Polish Solidarity movement and the possibility of Gorbachev-style political liberalisation. In 1989, revolts began across Eastern Europe and China against communist regimes. In China, the government refused to negotiate with student protestors, resulting in the Tiananmen Square attacks that stopped the revolts by force. The opening of a border gate between Austria and Hungary at the Pan-European Picnic on August 19, 1989, then set in motion a peaceful chain reaction, at the end of which there was no longer a GDR and the Eastern Bloc had disintegrated. It was the largest escape movement from East Germany since the Berlin Wall was built in 1961. But with the mass exodus at the Pan-European Picnic, the subsequent hesitant behavior of the Socialist Unity Party of East Germany and the non-intervention of the Soviet Union broke the dams. The revolts culminated with the revolt in East Germany against the communist regime of