U.S. Joint Chiefs of Staff authorize combat missions by Operation Farm Gate pilots. With this order, U.S. Air Force pilots were given the go-ahead to undertake combat missions against the Viet Cong as long as at least one Vietnamese national was carried on board the strike aircraft for training purposes. The program had initially been designed to provide advisory support to assist the South Vietnamese Air Force in increasing its capability. The gradual but dramatic expansion of Operation Farm Gate reflected the increasing involvement of the United States in Vietnam.
President John F. Kennedy originally ordered the Air Force to send a combat detachment to South Vietnam to assist the Saigon government in developing its own counterinsurgency capability. The Air Force formed the 4400th Combat Crew Training Squadron, which arrived at Bien Hoa Airfield in November 1961. Under Operation Farm Gate, the 4400th used older, propeller-driven aircraft to train South Vietnamese Air Force personnel. With the new order from the Joint Chiefs, the 4400th mission was expanded to include limited combat missions in support of South Vietnamese ground forces.
Farm Gate pilots began flying reconnaissance missions and providing logistical support to U.S. Army Special Forces units. The rules of engagement for combat missions dictated that American pilots only fly missions that the South Vietnamese were unable to undertake. The first Operation Farm Gate mission was flown on December 16, 1961. However, by late 1962, the communist activity and combat intensity had increased so much that President John F. Kennedy ordered a further expansion of Farm Gate. In early 1963, additional aircraft arrived and new detachments were established at Pleiku and Soc Trang.
In early 1964, Farm Gate was upgraded again with the arrival of more modern aircraft. By March 1965, Washington had altogether dropped the requirement that a South Vietnamese national be carried on combat missions. In October 1965, another squadron of A-1E aircraft was established at Bien Hoa. Secretary of Defense Robert McNamara approved the replacement of South Vietnamese markings on Farm Gate aircraft with regular U.S. Air Force markings. By this point in the war, the Farm Gate squadrons were flying 80 percent of all missions in support of the Army of the Republic of Vietnam (ARVN). With the buildup of U.S. combat forces in South Vietnam and the increase in U.S. Air Force presence there, the role of the Farm Gate program gradually decreased in significance. The Farm Gate squadrons were moved to Thailand in 1967, where they launched missions against the North Vietnamese forces in Laos.