In a dramatic confirmation of the growing rift between the two most powerful communist nations in the world, troops from the Soviet Union and the People's Republic of China fire on each other at a border outpost on the Ussuri River in the eastern region of the USSR, north of Vladivostok. In the years following this incident, the United States used the Soviet-Chinese schism to its advantage in its Cold War diplomacy.
The cause of the firefight between Soviet and Chinese troops was a matter of dispute. The Soviets charged that Chinese soldiers crossed the border between the two nations and attacked a Soviet outpost, killing and wounding a number of Russian guards. The intruders were then driven back with heavy casualties. The Chinese report indicated that it was the Soviets who crossed the border and were repulsed. Either way, it was the first time that either side openly admitted to a clash of arms along the border, though it had been rumored for years that similar run-ins were occurring. Ever since the early-1960s, relations between the two communist superpowers had deteriorated. China charged that the Soviet leadership was deviating from the pure path of Marxism, and by the mid-1960s, Chinese leaders were openly declaring that the United States and the Soviet Union were conspiring against the Chinese Revolution.
For the United States, the breakdown of relations between the Soviet Union and China was a diplomatic opportunity. By the early 1970s, the United States began to initiate diplomatic contacts with China. (Relations between the two nations had been severed in 1949 following the successful communist revolution in China.) In 1972, President Richard Nixon surprised the world by announcing that he would visit China. The strongest impetus for this new cordiality toward communist China was the U.S. desire to use the new relationship as leverage in its diplomacy with the Soviet Union, making the Russians more malleable on issues such as arms control and their support of North Vietnam in the on-going Vietnam War. Pitting these two communist giants against one another became a mainstay of U.S. diplomacy in the later Cold War era.