U.S. Defense Secretary Ash Carter responds to a reporter's question during a press conference on Camp David, Md., March 23, 2015, following a meeting with U.S. Secretary of State John F. Kerry, Afghan President Ashraf Ghani and Chief Executive Abdullah Abdullah. Carter earlier hosted the Afghan leaders for a visit at the Pentagon, where Ghani thanked U.S. service members and veterans who served in Afghanistan for their efforts and sacrifices.