After the war ended, Stewart was offered a regular commission and accepted it. He attended the Aircraft Maintenance Officer course at
Chanute Field in
Illinois, and in 1947 he returned to the University of Michigan, from which he received a
Bachelor of Science degree in aeronautical engineering in 1948. He was then assigned to the
Air Proving Ground at
Eglin Air Force Base, where he pioneered techniques for long-range flying using cruise control, and the delivery of
nuclear weapons from jet
fighter aircraft. In 1952, during the
Korean War, Stewart was posted to
Far East Air Force headquarters in
Tokyo, Japan, where he established requirements for equipment, supervised local modifications, and developed the nuclear delivery capability of the
Republic F-84 Thunderjet fighters. In 1954 he became the Far Eastern Air Force assistant deputy chief of staff for operations. He later wrote a book,
Airpower – The Decisive Force in Korea (1958). Stewart returned to the United States in 1955, and was assigned to U.S. Air Force (USAF) headquarters in
Washington D.C., where he was involved with development planning, eventually becoming the assistant chief of staff for development planning. He attended the
Industrial College of the Armed Forces from August 1959 to June 1960, and then was assigned to the
Air Research and Development Command (ARDC) at
Andrews Air Force Base in
Maryland as assistant deputy chief of staff for programming, and then as assistant deputy chief of staff for systems when the ARDC became the
Air Force Systems Command. He received a
master of business administration degree from
George Washington University in 1963. In August 1964 General Stewart was assigned to the
Office of the Secretary of the Air Force as the director, Office of Space Systems. As such he was also the staff director of the
National Reconnaissance Office. After briefly serving at the USAF headquarters as director of space in early 1967, he became the vice director of the
Manned Orbiting Laboratory program in March. After the project was cancelled he became deputy chief of staff for systems at the Air Force Systems Command, and then in June 1970, assumed command of the Aeronautical Systems Division at
Wright-Patterson Air Force Base in Ohio. He retired as a on 1 September 1976 with the rank of
lieutenant general. Stewart's decorations included the
Distinguished Service Medal, the
Legion of Merit with
oak leaf cluster, the
Distinguished Flying Cross, the
Bronze Star Medal, the Air Medal with six oak leaf clusters, the
Army Commendation Medal,
Air Force Commendation Medal with oak lef cluster, French
Croix de Guerre 1939–1945 and the
United Nations Service Medal. ==Later life==