Chairman of the Joint Chiefs of Staff U.S. Army Gen. Martin E. Dempsey, left, laughs with British Prime Minister David Cameron, right, after their meetings as a part of a defense chiefs strategic dialogue with the U.S. Joint Chiefs of Staff and their British counterparts, June 10, 2014, in London. (DoD photo by Mass Communication Specialist 1st Class Daniel Hinton, U.S. Navy/Released)