For 12 years, the United States was engaged in a futile war, trying to prevent South Vietnam, known then as the Republic of Vietnam, from being taken over by the North(the Democratic Republic of Vietnam). The United States' involvement in Vietnam began in the early 1960s, a time when many Asian countries were trying to achieve independence from their colonial rulers. The Communists had just defeated the Kuomintang in China, and non-Communist countries were alarmed at the possibility of nationalists being supported by Communist China or the Soviet Union. Audrey Seah, Culture of the World Vietnam.