On 14 January 2004, the 420th Air Base Group (420 ABG) was established at RAF Fairford to improve the control of its geographically separated units (GSUs) that had been aligned beneath the 100th Air Refueling Wing at RAF Mildenhall. These units are assigned to airfields at RAF Fairford, RAF Croughton, RAF Alconbury, and RAF Molesworth. The 420 ABG reported directly to Third Air Force until 26 May 2004, when the 38th Combat Support Wing (38 CSW) was established at Sembach Annex, Germany.