Defense Secretary Ash Carter announces the choices of Navy Adm. John M. Richardson, left, to serve as chief of naval operations and Army Gen. Mark A. Milley to serve as Army chief of staff during a briefing at the Pentagon, May 13, 2015. If confirmed by the Senate, Milley would succeed Army Gen. Ray Odierno and Richardson would succeed Navy Adm. Jonathan W. Greenert. Both Odierno and Greenert plan to retire.