U.S. Navy and Japanese ships have mounted a search for a missing sailor reported overboard from the guided-missile destroyer USS Stethem during operations in the South China Sea on Tuesday.

Officials from U.S. Pacific Fleet told Military.com that the Stethem made a man-overboard report around 9 a.m. local time Tuesday.

Although the crew conducted multiple searches of the ship, the sailor remained missing. The Stethem, which is homeported in Yokosuka, Japan, had been conducting routine operations in the region at the time, officials said.

The search for the sailor was first reported by Defense News.

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Two Japan Maritime Self Defense Force ships, the helicopter carrier Izumo and the destroyer Sazanami, have joined the Stethem in the search, along with helicopters from Izumo, officials said. The Joint Personnel Recovery Center Hawaii has also provided assistance.

Navy officials have not publicly identified the sailor as the search is ongoing.

This is the third man-overboard hunt for the Navy this year. A 50-hour search was conducted after Petty Officer Third Class Peter Mims was reported missing from the guided-missile cruiser Shiloh off the coast of Okinawa on June 8.

Shockingly, after the search was called off and Mims presumed dead, the sailor was discovered June 15, having spent a week hiding aboard the ship and actively avoiding other crew. He now faces possible discharge from the Navy.

An earlier search off the coast of North Carolina ended more tragically. Fire Controlman 2nd Class Christopher W. Clavin went missing June 6 from the cruiser Normandy. After a 76-hour search that spanned some 6,300 miles, the Navy called off its search for Clavin. Officials announced he was presumed dead.

-- Hope Hodge Seck can be reached at hope.seck@military.com. Follow her on Twitter at @HopeSeck.