Components of the 12th AF, also under Cannon, were assigned to his various MATAF sub-commands after the 12th's heavy bomb groups (and three B-26 medium bomb groups that were eventually returned to the 12th) were transferred to the newly created Fifteenth Air Force (1 November 1943; briefly under Doolittle and then Twining) as part of MASAF. In January 1944, Doolittle took over the 8th AF in England which along with the 15th AF in Italy, formed the United States Strategic Air Forces (USSTAF) under former 12th AF, NAAF, and 8th AF commander Spaatz.