Passing the Flag Defense Secretary James N. Mattis receives U.S. Northern Command's flag from Air Force Gen. Lori J. Robinson signifying her relinquishment of command during Northcom's change-of-command ceremony at Peterson Air Force Base, Colo., May 24, 2018. DoD photo by Tech. Sgt. Joe Laws SHARE: Download: Full Size (0.16 MB) Credit: Tech. Sgt. Joe Laws VIRIN: 180524-F-ZZ999-032A.JPG Photo Gallery