Since the founding of the People's Republic of China, Sino-U.S. relations have developed by twists and turns. Tying up with the changing postwar international situation, the development passed through different stages each covering roughly a decade.
From the late 1940s to the late 1950s was a period of confrontation between the "two world camps." Throughout this period, China was blockaded, besieged and looked upon with enmity. For well-known reasons, China and the United States met on the battlefield in Korea.
The next decade saw important changes in the "two world camps." It was a period in which the Soviets built up their strength while the United States was bogged down in the Vietnam War. Soviet expansionism showed itself with increasing clarity. During this decade, a number of factors making for better U.S.-China relations were already emerging. But there was not yet a fundamental change in their confrontation.
The 1970s was a period in which the United States and the Soviet Union attempted but failed to achieve a new balance of force through "détente." As Chairman Mao Zedong pointed out, "The United States wants to protect its interests in the world and the Soviet Union wants to expand; this can in no way be changed." In those ten years, it became increasingly clear that Soviet-U.S. rivalry was intensifying, and it became the source of turmoil and tension in the present-day world. However, the two rivals were in different positions. Strategically, the Soviet Union had already gone onto the offensive on a global scale after an all-round expansion of its strength, mainly its military strength. On the other hand, the United States, as former President Nixon said in his 1971 speech at Kansas City, was "no longer in the position of complete preeminence or predominance." Faced with Soviet threats and challenges at every turn, it switched over to the strategic defensive step by step.
In view of the changed international situation, Chairman Mao Zedong, who had for a long