NELLIS AIR FORCE BASE, Nev. --   Brig. Gen. Robert Novotny, 57th Wing commander, passes the guidon to Col. John Gallemore, 57th Adversary Tactics Group (ATG), during the 57th ATG change of command inside the Thunderbirds hangar on Nellis Air Force Base, Nev., July 1, 2019. 57th ATG boasts the world’s most capable and professional aggressor force to train US personnel and coalition partners during exercises and deployments, while overseeing USAF wide air, air Defense, space and information Aggressor initiatives and threat academic programs. (U.S. Air Force photo by Airman 1st Class Bryan Guthrie)