By the 1980s, however, the Soviet economy was in shambles. Because of a lack of incentives and, ironically, a more tolerant central government, workers did not put much effort into their duties. Nonetheless, the Soviet Union continued to build the military even though at times such spending took up half the country's revenue. Mikhail Gorbachev tried to reform the economy, but he took only limited steps (see perestroika and glasnost). When he lifted the Brezhnev Doctrine and allowed Poland's Solidarity to usurp that country's communist regime, the entire Warsaw Pact collapsed, soon followed by the Soviet Union itself.