Vietnam ground combat operations in 1965, and at their peak they numbered more than 500,000. The US also engaged in a sustained aerial bombing campaign. Meanwhile, China and the Soviet Union provided North Vietnam with significant material aid and 15,000 combat advisers. Communist forces supplying the Việt Cộng carried supplies along the Hồ Chí Minh trail, which passed through the Kingdom of Laos. The communists attacked South Vietnamese targets during the 1968 Tết Offensive. Although the campaign failed militarily, it shocked the American establishment, and turned US public opinion against the war. During the offensive, communist troops massacred over 3,000 civilians
Vietnam at Huế. Facing an increasing casualty count, rising domestic opposition to the war, and growing international condemnation, the US began withdrawing from ground combat roles in the early 1970s. This process also entailed an unsuccessful effort to strengthen and stabilise South Vietnam. Following the Paris Peace Accords of 27 January 1973, all American combat troops were withdrawn by 29 March 1973. In December 1974, North Vietnam captured the province of Phước Long and started a full-scale offensive, culminating in the fall of Saigon on 30 April 1975. South Vietnam was briefly ruled by a provisional government for almost eight years