When Mikhail Gorbachev became general secretary of the Communist Party of the Soviet Union in March 1985, he inherited a policy toward Iran that was a product of several factors. First, the Soviet Union, and Russia before it, had long declared its interest in its southern neighbor. Throughout the years since 1917, the USSR negotiated a treaty with Teheran in 1921 and in 1946; and in one of the first postwar crises, Soviet troops remained in Iran after the expiration of the World War II occupation agreement. In the 1960s and 1970s, the Kremlin and Teheran enjoyed a period of blossoming economic and political ties.