CIA activities in Vietnam the next 14 years, the focus of their paramilitary operations changed over time. Until 1964, the Hmong fighters in Laos focused on trying to fight back North Vietnamese fighters and on preventing further encroachment. They were highly important, because the US hadn't begun putting troops on the ground in any great numbers, yet. After that, in 1965, the report describes the Hmong activities in Laos as "flitt[ing] over mountain trails or mov[ing] by air to occupy key high ground and to harass Hanoi's tanks and artillery," meaning that US troops took on a frontline role and asked the paramilitary forces
1971 in the Vietnam War Exchanges in South Vietnam. President Nixon ordered the initiation of Operation Proud Deep Alpha, an intensive five-day bombing campaign against military targets in North Vietnam just north of they border above the 17th parallel of latitude. The number of U.S. military personnel in South Vietnam totaled 156,800, down from more than 500,000 three years earlier. 1971 in the Vietnam War U.S. military personnel in South Vietnam totaled 334,600 on 31 December 1970. The United States Congress adopted the revised Cooper-Church Amendment which prohibited the introduction of U.S. ground troops or advisers into Cambodia and declared that U.S. aid to Cambodia