Reagan's foreign policy stance was resolutely anti-communist; its plan of action, known as the Reagan Doctrine, sought to roll back the global influence of the Soviet Union in an attempt to end the Cold War. Under this doctrine, the Reagan administration initiated a massive buildup of the United States military; promoted new technologies such as missile defense systems; and, in 1983, undertook an invasion of Grenada, the first major overseas action by U.S. troops since the end of the Vietnam War. The administration also created controversy by granting aid to paramilitary forces seeking to overthrow leftist governments, particularly in war-torn Central America and Afghanistan. Specifically, the Reagan administration engaged in covert arms sales to Iran to fund Contra rebels in Nicaragua that were fighting to overthrow their nation's socialist government; the resulting scandal led to the conviction or resignation of several administration officials. During Reagan's second term, he sought closer relations with Soviet leader Mikhail Gorbachev, and the two leaders signed a major arms control agreement known as the INF Treaty.