1970-1991

Nixon becomes the first U.S. president to visit China, meeting with Mao Tse-tung on February 21. The two countries issue a communique recognizing their "essential differences" while making it clear that "normalization of relations" was in all nations' best interests. The rapprochement changes the balance of power with the Soviets.

On January 27, 1973, the United States, South Vietnam, North Vietnam and the Viet Cong sign the Paris Peace Treaty, establishing a cease-fire and a 60-day window for the withdrawal of all U.S. troops. The United States is allowed to continue providing aid to South Vietnam. Saigon falls in April 1975.

The communist Khmer Rouge takes power in Cambodia on April 16. Cambodia's educated and urban population is forced into the countryside as part of a state experiment in agrarian communism. Under the regime of Pol Pot, as many as 3 million Cambodians die from 1975 to 1979.

On December 25, 100,000 Soviet troops invade Afghanistan as communist Babrak Karmal seizes control of the government. U.S.-backed Muslim guerrilla fighters wage a costly war against the Soviets for nearly a decade before Soviet troops withdraw in 1988.

On August 14, electrician Lech Walesa leads massive strikes at the Lenin shipyards in Gdansk, Poland. The strikes soon spread to other cities and form the nucleus of the Solidarity movement. The communist government of Edward Gierk concedes to worker demands on August 31, recognizing their right to form unions and strike.

On March 23, Reagan outlines his Strategic Defense Initiative, or "Star Wars," a space-based defensive shield that would use lasers and other advanced technology to destroy attacking missiles far above the Earth's surface. Soviets accuse the U.S of violating the 1972 Antiballistic Missile Treaty.

On March 11, Gorbachev comes to power in the Soviet Union, ushering in an era of economic reforms under perestroika and greater political freedoms under glasnost.

On December 8, Reagan and Gorbachev sign the Intermediate Range Nuclear Forces Treaty in Washington. It mandates the removal of more than 2,600 medium-range nuclear missiles from Europe, eliminating the entire class of Soviet SS-20 and U.S. Cruise and Pershing II missiles.

Gorbachev renounces the Brezhnev Doctrine, which pledged to use Soviet force to protect its interests in Eastern Europe. On September 10, Hungary opens its border with Austria, allowing East Germans to flee to the West. After massive public demonstrations in East Germany and Eastern Europe, the Berlin Wall falls on November 9.

At a September 12 meeting in Moscow, the United States, Soviet Union, Great Britain, France and the two Germanys agree to end Allied occupation rights in Germany. On October 3, East and West Germany unite as the Federal Republic of Germany.

While vacationing in the Crimea, Gorbachev is ousted in a coup by Communist hard-liners on August 19. The coup soon falters as citizens take to the streets of Moscow and other cities in support of Russian President Boris Yeltsin, who denounced the coup. Military units abandon the hard-liners, and Gorbachev is released from house arrest. He officially resigns on December 25 as the Soviet Union is dissolved.