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 War South Korea (a.k.a. the Republic of Korea, ROK) had the second-largest contingent of foreign troops in South Vietnam after the United States. In November 1961, President Park Chung-hee proposed South Korean participation in the war to John F. Kennedy, but Kennedy disagreed as they were not SEATO treaty members. On 1 May 1964, Lyndon Johnson agreed to permit South Korean participation under the Many-Flags Program in return for monetary compensation. The first South Korean troops began arriving in 1964 and large combat formations began arriving a year later. The ROK Marine Corps dispatched their 2nd Marine Brigade, while the ROK