THUNDERBIRDS U.S. Secretary of Defense Robert M. Gates meets with members of the U.S. Air Force Thunderbirds upon his arrival at Peterson Air Force Base, Colo., May 29, 2007. Gates is in Colorado Springs to deliver the commencement speech for the U.S. Air Force Academy graduation, May 30, 2007. SHARE IMAGE: Download Image: Full Size (0.03 MB) Photo By: VIRIN: 466743-V-PVK18-497.jpg Photo Gallery