Capstone Comments Defense Secretary Jim Mattis speaks with students in the Capstone General and Flag Officer course at the Pentagon, Aug. 8, 2017. The Capstone curriculum examines major issues affecting national security, military strategy and interoperability. DoD photo by Air Force Tech. Sgt. Brigitte N. Brantley SHARE: Download: Full Size (1.52 MB) Credit: Brigitte N. Brantley VIRIN: 170808-D-GO396-0197.JPG Photo Gallery