The U.S. Navy has identified an officer who went missing Tuesday from the USS Stethem in waters near the Philippines.

Lt. Steven Hopkins disappeared just weeks after he checked aboard the guided-missile destroyer to be the ship's chief engineer.

Hopkins graduated from the Citadel in 2009 and served previous tours of duty aboard two other warships.

His disappearance remains under investigation, Navy officials said.

The ship was about 140 miles west of Subic Bay, Philippines, at the time when Hopkins’ disappearance was noticed.

Two Chinese warships shadowing the USS Stethem accompanied U.S. ships in a search for Hopkins, U.S. officials said, adding that Japanese vessels also participated.

In July the USS Stethem sailed near a contested island in the South China Sea that has been claimed by China in what the Pentagon called a “freedom of navigation” operation.