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
CIA activities in Vietnam A series of accusations in the early 1970s that the CIA was complicit in drug trafficking in Laos was a contributing factor in the public's opposition to US activities in Southeast Asia. Neither the CIA nor any of its officers were accused of direct activity in the narcotics operations, and it is likely that the agency did not focus much energy on the trafficking by indigenous allies until a heroin epidemic broke out among US troops in South Vietnam. There was nothing preventing the hill tribes in northern Laos from producing and selling opium until 1971, as the trade was