200522-N-AJ005-1018 SOUTH CHINA SEA (May 22, 2020) Machinist Mate Fireman Christopher Macdonald, assigned to the Arleigh Burke-class guided-missile destroyer USS Mustin (DDG 89), exits a watertight door during an engineering drill. Mustin is underway conducting operations in support of security and stability in the Indo-Pacific while 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 3rd Class Cody Beam/Released)