As the war wound down, the Nixon administration was able to deal pragmatically with the major communist powers. The most dramatic step was opening ties to the People's Republic of China. In the two decades since Mao Zedong's victory, the United States had argued that the Nationalist government on Taiwan represented all of China. In 1971 and 1972, Nixon softened the American stance, eased trading restrictions and became the first American president ever to visit Beijing.
With the Soviet Union, Nixon was equally successful in pursuing a policy of detente. Several months after his trip to China, he visited the Soviet Union. He held several cordial meetings with Soviet leader Leonid Brezhnev in which they agreed to limit stockpiles of missiles, cooperate in space and ease trading restrictions. The Strategic Arms Limitation Talks (SALT) culminated in 1972 in an arms control agreement limiting the growth of nuclear arsenals and restricting anti-ballistic missile systems.
Source: U.S. Department of State