The main conflict in the Vietnam War was primarily between the communist government of North Vietnam and the non-communist government of South Vietnam, along with its principal ally, the United States. The war was rooted in the struggle against colonialism and the Cold War tensions between the U.S. and the Soviet Union. U.S. involvement escalated in the 1960s due to fears of the spread of communism, which led to a protracted and highly controversial conflict. The war lasted from approximately 1955 to 1975, resulting in significant loss of life and long-term social and political repercussions for Vietnam and the U.S.