During his rule, Brezhnev supported "détente", a passive weakening of animosity with the West with the goal of improving political and economic relations. However, by the 25th Congress held in 1976, political, economic and social problems within the Soviet Union began to mount, and the Brezhnev administration found itself in an increasingly difficult position. The previous year, Brezhnev's health began to deteriorate. He became addicted to painkillers and needed to take increasingly more potent medications to attend official meetings. Because of the "trust in cadres" policy implemented by his administration, the CPSU leadership evolved into a gerontocracy. At the end of Brezhnev's rule, problems continued to amount; in 1979 he consented to the Soviet intervention in Afghanistan to save the embattled communist regime there and supported the oppression of the Solidarity movement in Poland. As problems grew at home and abroad, Brezhnev was increasingly ineffective in responding to the growing criticism of the Soviet Union by Western leaders, most prominently by US Presidents Jimmy Carter and Ronald Reagan, and UK Prime Minister Margaret Thatcher. The CPSU, which had wishfully interpreted the financial crisis of the 1970s as the beginning of the end of capitalism, found its country falling far behind the West in its economic development. Brezhnev died on 10 November 1982, and was succeeded by Yuri Andropov on 12 November.