The war in Vietnam lasted from 1957 to 1975 and involved major military participation from the United States and support from the Soviet Union and China for North Vietnam. The war began as an internal conflict in South Vietnam but grew to include North Vietnam and other international powers. By the end of 1965, there were around 185,000 American troops in South Vietnam supporting its government, and at the peak of US involvement over 500,000 American troops were deployed in an effort to defeat North Vietnamese and National Liberation Front forces through large-scale search and destroy operations. Despite massive US bombing campaigns and troop deployments, the US and South Vietnam were ultimately unable to gain a military victory, resulting in America withdrawing from the war in 1973 and a Communist victory