In October 1945, Foss was ordered to appear at Navy Day ceremonies in four cities there and was finally relieved from active duty in December 1945 but was retained in the Marine Corps Reserve on inactive duty until 1947. In 1946, Foss was appointed a Lieutenant Colonel in the South Dakota Air National Guard and instructed to form the South Dakota Air National Guard, becoming the Commanding Officer for the Guard's 175th Fighter-Interceptor Squadron. During the unit's formative years, Foss was actively involved in administration and flying with the squadron, even becoming a member of their North American P-51 Mustang air demonstration team."114th Fighter Wing, South Dakota Air National Guard." South Dakota Department of the Military and Department of Veterans Affairs. Retrieved: August 4, 2011. During the Korean War, Foss, then a Colonel, was called to active duty with the United States Air Force, relinquishing command of the 175th Squadron, and served as a Director of Operations and Training for the Central Air Defense Command; he eventually reached the rank of Brigadier General."Joe Foss" Century of Flight, 2003. Retrieved: August 4, 2011.
In October 1945, Foss was ordered to appear at Navy Day ceremonies in four cities there and was finally relieved from active duty in December 1945 but was retained in the Marine Corps Reserve on inactive duty until 1947. In 1946, Foss was appointed a Lieutenant Colonel in the South Dakota Air National Guard and instructed to form the South Dakota Air National Guard, becoming the Commanding Officer for the Guard's 175th Fighter-Interceptor Squadron. During the unit's formative years, Foss was actively involved in administration and flying with the squadron, even becoming a member of their North American P-51 Mustang air demonstration team."114th Fighter Wing, South Dakota Air National Guard." South Dakota Department of the Military and Department of Veterans Affairs. Retrieved: August 4, 2011. During the Korean War, Foss, then a Colonel, was called to active duty with the United States Air Force, relinquishing command of the 175th Squadron, and served as a Director of Operations and Training for the Central Air Defense Command; he eventually reached the rank of Brigadier General."Joe Foss" Century of Flight, 2003. Retrieved August 4, 2011.