The 137th Air Refueling Group is an associate unit of the Oklahoma Air National Guard stationed at Tinker Air Force Base, Oklahoma. If activated for federal service, the group is gained by Air Mobility Command. As of July 2015, the group is in the process of returning to Will Rogers Air National Guard Base and converting from the air refueling to the special operations mission.The group was first activated during World War II as the 404th Fighter Group flying Republic P-47 Thunderbolts.