Along with the Kansas ANG F-100C 127th Tactical Fighter Squadron, the 166th TFS was federalized and deployed to Kunsan Air Base, South Korea. The federalized ANG squadrons were assigned as part of the 354th Tactical Fighter Wing. The squadrons flew deterrent air defense missions over South Korean airspace during the next year. During the deployment some pilots flew combat missions in South Vietnam while performing temporary assignments with other units. The performance of the ANG units at Kusan in 1968–69 suggested the prerequisites of effective air reserve programs and paved the way for adoption of the total force policy in 1970 which exists today. In 1971 the squadrons F-100Cs were retired and replaced by F-100D/F Super Sabres, being received from combat units in South Vietnam that were returning to the United States.