SOUTH CHINA SEA (Nov. 14, 2020) The Arleigh Burke-class guided-missile destroyer USS John S. McCain (DDG 56) fires its mark-38 25mm gun during a live-fire gunnery exercise. John S. McCain is assigned to Destroyer Squadron (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)