161220-N-KP948-040 GAETA, Italy (Dec. 20, 2016) - Petty Officer 3rd Class Carl Mastenbrook and Petty Officer 1st Class James Smith give training on toxic gas equipment aboard USS Donald Cook (DDG 75), Dec. 20, 2016. Donald Cook, an Arleigh-Burke class guided-missile destroyer, forward-deployed to Rota, Spain, is conducting naval operations in the U.S. 6th Fleet area of operations in support of U.S. national security interests in Europe and Africa. (U.S. Navy photo by Petty Officer 3rd Class Alyssa Weeks/Released)