The 515th Air Defense Group is a disbanded United States Air Force (USAF) organization. Its last assignment was with the 31st Air Division, stationed at Duluth Municipal Airport, Minnesota where it was inactivated in 1955. The group was originally activated as a support unit for a combat group at the end of World War II in Italy and then redeployed to Okinawa, where it continued that mission until it was inactivated in 1945.