During the Vietnam War, a "secret war" was fought across the fence in Laos, Cambodia and North Vietnam, unknown to the media or the public, under the aegis of the Military Assistance Command Vietnam's top secret Studies and Observation Group. SOG's chain of command for missions and after-action reports extended to the White House and the Joint Chiefs of Staff. Small Green Beret-lead teams ran missions into Laos, Cambodia, and North Vietnam without assistance from conventional artillery, tank or infantry units. Once on the ground, their sole support was provided by Air Force Tactical Air and helicopter units, U.S. Army and Marine helicopter aviation personnel and aircrews, and from the South Vietnam Air Force's 219th Special Operations Squadron, code named Kingbees. In Laos, the communists dedicated 50,000 troops to the Ho Chi Minh Trail, including highly trained sappers from the 305th Sapper Battalion, its sole mission: attack SOG teams