Chairman of the Joint Chiefs of Staff U.S. Army Gen. Martin E. Dempsey answers a question posed by moderator Lesley Stahl during the Aspen Security Forum in Aspen, Colo., July 24, 2014. The forum is held every summer on the campus of the Aspen Institute and consists of panel discussions as well as in-depth conversations with leaders involved in government security issues. (DoD photo by Staff Sgt. Sean K. Harp, U.S. Army/Released)