Defense Visit Acting Defense Secretary Patrick M. Shanahan walks with Air Force Gen. Terrence J. O’Shaughnessy, commander of U.S. Northern Command and North American Aerospace Defense Command, during his visit to Peterson Air Force Base, Colo., April 9, 2019. SHARE IMAGE: Download Image: Full Size (0.38 MB) Tags: NORAD, Shanahan, Northern Command, Space, Acting Defense Secretary Photo By: Lisa Ferdinando, DOD VIRIN: 190409-D-BN624-0217A.JPG Photo Gallery