170728-N-FP878-901 ATLANTIC OCEAN (July 28, 2017) Fifty-caliber machine gun casingslay on the floor aboard the Arleigh Burke-class guided-missile destroyer USS Donald Cook (DDG 75). Donald Cook is forward-deployed to Rota, Spain, conducting its sixth patrol in the U.S. 6th Fleet area of operations. (U.S. Navy photo by Mass Communication Specialist 1st Class Theron J. Godbold /Released)