He returned to the United States and the Pentagon in December 1947, with assignment to the office of the Deputy Chief of Staff—Materiel, Headquarters United States Air Force, for duty with the Special Weapons Group as assistant to Major Gen. William E. Kepner, Deputy Chief for Atomic Energy. On 1 July 1948, a reorganization moved the organization to the office of the Deputy Chief of Staff—Operations, and Hegenberger succeeded Kepner as chief of Special Weapons Group. In August 1948, under the Assistant For Atomic Energy, his position was retitled Chief, 1009th Special Weapons Squadron.