It is because of China's strive to be a hegemony in the world and because of the clashing of the capitalist vs. communist ideologies in their foreign policies, that caused hostility between the liberal-capitalist USA and the communist China through 1949 to 1991.
In just over two decades from its inception, the foreign policy of the Peoples Republic of China swung from formal alliance with the Soviet Union against the US, to de facto alliance with the US against the Soviet Union . From 1949 China was ruled by communist dictator Mao Zedong. For over a century the national interests of China have been reflected in the following foreign policy objectives of communist China: .
(a) to preserve the national territory from foreign annexation or intrusion;.
(b) To regain what had been lost through foreign interventions;.
(c) To repel from her borders any threatening or hostile military presence, be it Russian, Japanese, America or any of her power; and.
(d) To regain for China the status of a world power commensurate with the greatness of her civilisation. China is determined to regain its rightful place as a global power, and to be recognised, respected and deferred to as such in the affairs of the world. To gain great power status, China sees it as essential to reunify its national territory, modernise and develop its economy and build a powerful military . The foreign policy objectives of a communist China however are not purely national in spirit, because Mao firmly believed in the ideological superiority of communism and claimed for China the role of leadership in the drive to world revolution. Thus, the export of communism thought and teachings, and the active encouragement or anti-imperialist movements in developing countries, were additional objectives in Chinese foreign policy. In contrast the communist leadership appeared purposeful and resolute; its followers were loyal and dedicated.