U.S. Army Command Sgt. Maj. John W. Troxell, senior enlisted advisor to the chairman of the Joint Chiefs of Staff, signs a copy of the Noncommissioned Officer and Petty Officer handbook for a Marine Corps security guard assigned to the U.S. Embassy in Ankara, Turkey, Jan. 5, 2016. DoD photo by Navy Petty Officer 2nd Class Dominique A. Pineiro