The Communist Party of China defeated the Kuomintang in 1949. China had been in a state of civil war since 1927. There was the interruption of the Sino-Japanese War in 1937 . This escalated further with the hostilities of World War II. There was a momentary collaboration against the Japanese invasion during the war. The nature of geopolitics changed immensely. The Cold War had began after World War II and the US was engaged in the policy of containment. China went from ally to enemy. Mao Zedong who who serve as leader of the People’s Republic of China from 1949 to 1976 advocated anti-colonial politics and the promotion of communism. The US and China would be in conflict in both the Korean War and Vietnam War.Vietnam was a different scenario. The US never conducted a ground invasion of North Vietnam, because they were fearful of Chinese military action. Mao did not send troops to Vietnam, but did provide aid. If he did it would have most likely ended they way the Korean War did; a stalemate and ceasefire that the US found unacceptable. China’s rise shows the complications of decolonization and Cold War politics during the 20th century.