The Soviet Union accuses China of backing U.S. policies in Vietnam, an accusation that illustrates the growing rift between the two communist superpowers. China, which had previously taken a hard line toward negotiations between Hanoi and Washington, softened its position by endorsing a North Vietnamese peace plan for ending the war. Although the peace proposal was unacceptable to the United States, the fact that China advocated negotiations between Hanoi and Washington was significant. The Soviet Union, whose relations with China were already deteriorating, was highly suspicious of what they rightfully perceived as a “warming” in Sino-American relations. This suspicion only grew stronger in February 1972, when President Richard Nixon visited China.