The 421st Fighter Squadron is part of the 388th Fighter Wing at Hill Air Force Base, Utah. It operates the Lockheed Martin F-35A aircraft conducting air superiority missions. The squadron is one of the most decorated fighter squadrons in the United States Air Force, being awarded three Presidential Unit Citations and seven Air Force Outstanding Unit Awards for Valor in Combat.
The unit was originally formed as the 421st Night Fighter Squadron in 1943. After training, it was deployed to Fifth Air Force and ordered to New Guinea to provide air defense interceptor protection against Japanese night air raids on USAAF airfields. It later served in the Philippines Campaign where in addition to night interceptor missions it also flew day and night interdiction missions against enemy troop movements, bridges and other targets of opportunity. It later served on Okinawa and in Occupied Japan where it was inactivated in 1947.