President Donald J. Trump, left; his wife, Melania, Defense Secretary Jim Mattis and Marine Corps Gen. Joe Dunford, chairman of the Joint Chiefs of Staff, listen as Air Force Maj. Gen. Dondi E. Costin, chief of chaplains, gives the invocation during the 9/11 Observance Ceremony at the Pentagon, Sept. 11, 2017. DoD photo by Army Sgt. Amber I. Smith