Defense Secretary Ash Carter speaks during a press conference following a change-of-command ceremony for the North American Aerospace Defense Command and U.S. Northern Command at Peterson Air Force Base, Colo., May 13, 2016. Air Force Gen. Lori J. Robinson, second from left, assumed command of NORAD and Northcom during the ceremony. Also pictured are, from left, Marine Corps Gen. Joe Dunford, chairman of the Joint Chiefs of Staff; Canadian Defense Minister Harjit Sajjan; and Canadian Army Gen. Jonathan Vance, chief of the Canadian defense staff. DoD photo by Navy Petty Officer 2nd Class Dominique A. Pineiro