History of socialism under challenge from Solidarność, or Solidarity, a labor union under the leadership of Lech Wałęsa. The union was sufficiently threatening to the government that on 13 December 1981, the head of state, Wojciech Jaruzelski declared martial law, suspended the union, and imprisoned most of its leaders. Mikhail Gorbachev (born 1931), who took control in 1985, was the first Soviet leader to have been born after the October revolution. He is remembered for three initiatives: "glasnost", "perestroika", and the "Frank Sinatra doctrine". "Glasnost", or "openness", was Gorbachev's term for allowing public debate in the Soviet Union to an unprecedented degree. "Perestroika"
Foreign relations of the Soviet Union power struggles and foreign intervention, requested the neighboring Soviet Union to send military aid. Soviet intervention was seen as a hostile invasion by the United States and its allies, who funded the counter-revolutionary Mujahadeen, and thus led to a return to hostilities which were greatly exacerbated in the following years. When Mikhail Gorbachev became the leader of the Soviet Union in 1985, he sought to restructure the Soviet Union to resemble the Scandinavian model of western social democracy and thus create a private sector economy. He removed Soviet troops from Afghanistan and began a hands-off approach in the USSR's relations