Mattis Testimony Defense Secretary James N. Mattis and Air Force Gen. Paul J. Selva, vice chairman of the Joint Chiefs of Staff, testify on the National Defense Strategy and the Nuclear Posture Review before the House Armed Services Committee in Washington, D.C., Feb. 6, 2018. DoD photo by Navy Petty Officer 1st Class Kathryn E. Holm SHARE: Download: Full Size (0.64 MB) Credit: Kathryn E. Holm VIRIN: 180206-D-SH953-0090C.JPG Photo Gallery