In 1978, Gorbachev was appointed to the Central Committee's Secretariat for Agriculture, replacing his old friend Kulakov, who had died of a heart attack. Gorbachev concentrated his attentions on agriculture: the harvests of 1979, 1980, and 1981 were all poor, due largely to weather conditions, and the country had to import increasing quantities of grain. He had growing concerns about the country's agricultural management system, coming to regard it as overly centralized and requiring more bottom-up decision making; he raised these points at his first speech at a Central Committee Plenum, given in July 1978. He began to have concerns about other policies too. In December 1979, the Soviets sent the Red Army into neighbouring Afghanistan to support its Soviet-aligned government against Islamist insurgents; Gorbachev privately thought it a mistake. At times he openly supported the government position; in October 1980 he for instance endorsed Soviet calls for Poland's Marxist–Leninist government to crack down on growing internal dissent in that country. That same month, he was promoted from a candidate member to a full member of the Politburo, the highest decision-making authority in the Communist Party. At the time, he was the Politburo's youngest member.