in favour of détente. When Gorbachev visited Cuba in April 1989, he informed Castro that perestroika meant an end to subsidies for Cuba. Ignoring calls for liberalization in accordance with the Soviet example, Castro continued to clamp down on internal dissidents and in particular kept tabs on the military, the primary threat to the government. A number of senior military officers, including Ochoa and Tony de la Guardia, were investigated for corruption and complicity in cocaine smuggling, tried, and executed in 1989, despite calls for leniency. In Eastern Europe, socialist governments fell to capitalist reformers between 1989 and 1991 and many Western observers expected the same in Cuba. Increasingly isolated, Cuba improved relations with Manuel Noriega's right-wing government in Panama – despite Castro's personal hatred of Noriega – but it was overthrown in a US invasion in December 1989. In February 1990, Castro's allies in Nicaragua, President Daniel Ortega and the Sandinistas, were defeated by the US-funded National Opposition Union in an election. With the collapse of the Soviet bloc, the US secured a majority vote for a resolution condemning Cuba's human rights violations at the United Nations Human Rights Commission in Geneva, Switzerland. Cuba asserted that this was a manifestation of US hegemony, and refused to allow an investigative delegation to enter the country. Special Period: 1992–2000 With favourable trade from the Soviet bloc ended, Castro publicly declared that Cuba was entering a "Special Period in Time of Peace". Petrol rations were dramatically reduced, Chinese bicycles were imported to replace cars, and factories performing non-essential tasks were shut down. Oxen began to replace tractors, firewood began being used for cooking and electricity cuts were introduced that lasted 16 hours a day. Castro admitted that Cuba faced the worst situation short of open war, and that the country might have to resort to subsistence farming. By 1992, Cuba's economy had declined by over 40% in under two years, with major food shortages, widespread malnutrition and a lack of basic goods. Castro hoped for a restoration of Marxism–Leninism in the USSR, but refrained from backing the 1991 coup in that country. When Gorbachev regained control, Cuba-Soviet relations deteriorated further and Soviet troops were withdrawn in September 1991. In December, the Soviet Union was officially dissolved as Boris Yeltsin abolished the Soviet Communist Party and introducing a capitalist multiparty democracy. Yeltsin despised Castro and developed links with the Miami-based Cuban American National