March 13 (Bloomberg) -- A U.S. Navy surveillance vessel on a submarine spotting mission has been joined by a U.S. destroyer in the South China Sea, according to a Pentagon official, days after the surveillance ship was allegedly harassed by Chinese boats.

The USNS Impeccable has been joined by the USS Chung-Hoon, a destroyer already on a routine deployment to the area but moved closer after five Chinese vessels, in a possibly coordinated effort, “shadowed and aggressively maneuvered in dangerously close proximity” to the surveillance vessel on March 8.

The U.S. State Department has lodged a protest with the Chinese government over the incident. China said the surveillance vessel broke international and Chinese laws and demanded an end to similar intelligence gathering missions.

The Impeccable was conducting routine submarine surveillance in international waters when the harassment occurred, the Pentagon official said. The Chung-Hoon wasn’t moved closer to the Impeccable to send a signal to China, the official said.

The U.S. claim that Chinese ships harassed a vessel in international waters is “totally inaccurate and confuses right and wrong,” China’s Foreign Ministry spokesman Ma Zhaoxu said March 10, adding the vessel was illegally in China’s exclusive economic zone.

The Impeccable will continue its mission with or without an escort, said the Pentagon official, who declined to say how long the Chung-Hoon would stay nearby.

Military Exchanges

The March 8 incident took place after the U.S. and China agreed to resume military exchanges that China froze in October to protest American arms sales to Taiwan.

The encounter occurred in international waters in the South China Sea, about 75 miles (120 kilometers) south of Hainan Island and was preceded by days of increasingly aggressive conduct by Chinese vessels, the Defense Department said.

The previous acts included a March 4 incident when a Chinese Bureau of Fisheries Patrol vessel used a high-intensity spotlight to illuminate the entire length of the ocean surveillance ship USNS Victorious several times, the U.S. said.

Impeccable and Victorious are part of the Military Sealift Command. Impeccable carries a crew of 25 civilian mariners and 25 military personnel, and Victorious has about 18 crewmembers, according to Navy Web pages on the vessels.

To contact the reporter on this story: Tony Capaccio at the Pentagon at at acapaccio@bloomnberg.net

Last Updated: March 13, 2009 00:13 EDT