OPERATIONS TOUR Deputy Defense Secretary Ashton B. Carter receives a tour of the 612 Air and Space Operations Center on Davis-Monthan Air Force Base, Tucson, Ariz., Sept. 26, 2012. Carter visited several installations on his trip. SHARE IMAGE: Download Image: Full Size (0.07 MB) Photo By: VIRIN: 982978-K-SBZ10-365.jpg Photo Gallery