The 398th Air Expeditionary Group is a provisional United States Air Force unit assigned to the United States Air Forces in Europe. The 398 AEG may be activated or inactivated at any time. During World War II, its predecessor unit, the 398th Bombardment Group (Heavy) was an Eighth Air Force B-17 Flying Fortress unit in England, stationed at RAF Nuthampstead. The group flew 195 combat missions, the last being on 25 April 1945.