** FILE ** Adm. Jonathan Greenert, chief of naval operations, gestures as he address the media in front of the USS Enterprise at Naval Station Norfolk on Saturday, Dec. 1, 2012, in Norfolk, Va., before an inactivation ceremony for the Enterprise, the first nuclear-powered aircraft carrier. The ship served in the fleet for 51 years. (AP Photo/Steve Helber)

Photo by: Steve Helber

** FILE ** Adm. Jonathan Greenert, chief of naval operations, gestures as he address the media in front of the USS Enterprise at Naval Station Norfolk on Saturday, Dec. 1, 2012, in Norfolk, Va., before an inactivation ceremony for the Enterprise, the first nuclear-powered aircraft carrier. The ship served in the fleet for 51 years. (AP Photo/Steve Helber)