EAST CHINA SEA (Aug. 19, 2020) Gas Turbine Systems Technician (Mechanical) 1st Class Yue Chang, from Fresno, Calif., evaluates a lube oil sample during an engineering training team (ETT) drill aboard the Arleigh Burke-class guided missile destroyer USS Halsey (DDG 97). Halsey 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 Andrew Langholf)