GATES' ADDRESS Defense Secretary Robert M. Gates addresses audience members at the U.S. Northern Command/ North American Aerospace Defense Command Change of Command ceremony on Peterson Air Force Base, Colo., May 19, 2010. Air Force Gen. Gene Renuart retired from 40 years of active duty service. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 314775-O-QCB44-857.jpg Photo Gallery