The squadron was first activated as the19th Observation Squadronin March 1942. The 19th originally flew antisubmarine missions duringWorld War II, then moved to China in 1944 to begin observation missions in support of Chinese ground forces. It later flew resupply missions to resistance forces operating behind enemy lines in French Indochina.
The squadron was redesignated the19th Tactical Air Support Squadron, then organized in July 1963. From 1963 through 1968 the 19th Tactical Air Support Squadron flew forward air support and observation missions over Vietnam until its mission was transferred to Osan AB, South Korea in 1972, where it provided Eighth US Army and Republic of Korea ground forces with aerial reconnaissance and close air support.