The United States participated in the Vietnam War.
1973 in the Vietnam War began with a peace agreement , the Paris Peace Accords , signed by the United States and South Vietnam on one side of the Vietnam War and communist North Vietnam and the insurgent Viet Cong on the other . The Vietnam War ( Chiến tranh Việt Nam ) , also known as the Second Indochina War , and known in Vietnam as Resistance War Against America ( Kháng chiến chống Mỹ ) or simply the American War , was a war that occurred in Vietnam , Laos , and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975 . The North Vietnamese army was supported by the Soviet Union , China and other communist allies and the South Vietnamese army was supported by the United States , South Korea , Australia , Thailand and other anti-communist allies .