Conference Photos Defense Secretary Jim Mattis takes pictures with airmen during the the Air Force Association Air, Space and Cyber Conference in National Harbor, Md., Sept. 20, 2017. Mattis delivered a keynote speech. DoD photo by Air Force Tech. Sgt. Brigitte N. Brantley SHARE IMAGE: Download Image: Full Size (0.97 MB) Photo By: Brigitte N. Brantley VIRIN: 170920-D-GO396-0032E.JPG Photo Gallery