The guided-missile frigate Yulin (Hull 569) attached to a destroyer flotilla with the navy under the PLA Southern Theater Command fires its rocket-propelled depth charges at mock hostile submarine during a maritime training exercise in waters of the South China Sea in late March, 2020. The guided-missile frigates Xuchang (536) and Yulin (Hull 569) jointly execute maritime tasks on subjects including formation maneuver, live-fire operation, anti-submarine warfare (ASW) operation, joint salvage, etc. (eng.chinamil.com.cn/Photo by Li Hongming and Li Wei)