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
1973 in the Vietnam War Nixon promised continued economic aid to South Vietnam, dependent upon U.S. congressional approval, and Thieu pledged to never ask the United States to reintroduce American troops into South Vietnam. The US and North Vietnam issued a joint communique calling on all parties to observe the 28 January ceasefire agreement with effect from 15 June. The Case–Church Amendment approved by the U.S. Congress and signed into law prohibited further U.S. military activity in Vietnam, Laos and Cambodia after 15 August 1973. This ended direct U.S. military involvement in the Vietnam War, although the U.S. continued to provide military equipment and economic