SOUTH CHINA SEA (Dec. 28, 2020) Cryptologic Technician (Collection) 3rd Class Jamekia Nelson, from Cleveland, prepares to conduct tactical room-clearing as part of the Navy Security Force Sentry (NSFS) course aboard the Arleigh Burke-class guided-missile destroyer USS John S. McCain (DDG 56). McCain is assigned to Destroyer Squadron Fifteen (DESRON 15), the Navy's largest forward-deployed DESRON and the U.S. 7th Fleet's principal surface force. (U.S. Navy photo by Mass Communication Specialist 2nd Class Markus Castaneda)