Cuban lives in these military endeavours; the anti-Castro Center for a Free Cuba has claimed that an estimated 14,000 Cubans were killed in foreign Cuban military actions. When American critics claimed that Castro had no right to interfere in these nations, he countered that Cuba had been invited into them, pointing out the US' own involvement in various foreign nations. Between 1979 and 1991 about 370, 000 Cuban troops together with 50, 000 Cuban civilians (mostly teachers and doctors) served in Angola, representing about 5% of Cuba's population. The Cuban intervention in Angola was envisioned as a short-term commitment, but the Angolan government used the profits from the oil industry to subsidize Cuba's economy, making Cuba as economically dependent upon Angola as Angola was militarily dependent upon Cuba. In the late 1970s, Cuba's relations with North American states improved during the period with Mexican President Luis Echeverría, Canadian Prime Minister Pierre Trudeau, and US President Jimmy Carter in power. Carter continued criticizing Cuba's human rights abuses, but adopted a respectful approach which gained Castro's attention. Considering Carter well-meaning and sincere, Castro freed certain political prisoners and allowed some Cuban exiles to visit relatives on the island, hoping that in turn Carter would abolish the economic embargo and stop CIA support for militant dissidents. Conversely, his relationship with China declined, as he accused Deng Xiaoping's Chinese government of betraying their revolutionary principles by initiating trade links with the US and attacking Vietnam. In 1979, the Conference of the Non-Aligned Movement (NAM) was held in Havana, where Castro was selected as NAM president, a position he held until 1982. In his capacity as both president of the NAM and of Cuba he appeared at the United Nations General Assembly in October 1979 and gave a speech on the disparity between the world's rich and poor. His speech was greeted with much applause from other world leaders, though his standing in NAM was damaged by Cuba's refusal to condemn the Soviet intervention in Afghanistan. Reagan and Gorbachev: 1980–1991 By the 1980s, Cuba's economy was again in trouble, following a decline in the market price of sugar and 1979's decimated harvest. For the first time, unemployment became a serious problem in Castro's Cuba, with the government sending unemployed youth to other countries, primarily East Germany, to work there. Desperate for money, Cuba's government secretly sold off paintings from national collections and illicitly traded for