Strategy 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 to the House Armed Services Committee, Feb. 6, 2018. DoD photo by Navy Petty Officer 1st Class Kathryn E. Holm SHARE IMAGE: Download Image: Full Size (0.67 MB) Tags: HASC, house armed services committee, Secretary of Defense , james mattis, JIm Mattis, Chaos, Kathryn Holm, Mass Communication Specialist Kathryn E. Holm, Gen. Paul J. Selva , Department of Defense, Photo, DoD, Defense Secretary , James N. Mattis, SecDef, Pentagon, Vice Chairman of the Joint Chiefs of Staff, MILITARY Photo By: Navy Petty Officer 1st Class Kathryn E. Holm VIRIN: 180206-D-SH953-0096.JPG Photo Gallery