The 1st Air Commando Squadron (ACS)/1st Special Operations Squadron (SOS) began combat operations in 1964, first flying out of BienHoa Air Base, and later out of Pleiku. The A-1 Skyraider was the primary aircraft flown during this period. In December 1967, the squadron began to shift its operations to Nakhon Phanom Royal Thai Air Force Base (NKP) in Northeastern Thailand along the Mekong River border with Laos. At NKP the 1st ACS was part of the 56th Air Commando Wing/56th SOW. It flew its last combat missions in November of 1972, the last U.S. squadron to fly A-1s in combat.

Squadron awards between 1964 and 1972: Five Presidential Unit Citations; Two Air Force Outstanding Unit Awards with Combat "V"; Two Air Force Outstanding Unit Awards; and the Republic of Vietnam Gallantry Cross with Palm.

USAF Congressional Medal of Honor winner Bernard F. Fisher earned his country’s highest decoration for bravery in 1966 while flying with the 1st ACS out of Pleiku Vietnam.