The Philippines on Friday announced that it will send its World War II vessel to a borderline part of the South China Sea after China headed its coastal patrol vessels in the waters.

U.S. in World War II used the BRP Rajah Humabon against Germany submarines, which will patrol around Scarborough Shoal, in the disputed sea, the Philippine Star reported on its website.

China sent the Haixun 31, a 3,000 ton vessel to inspect foreign ships and oil facilities in the South China Sea, a Hong Kong’s Ta Kung Pao newspaper reported on Thursday.

“The Navy conducts regular offshore patrols and we should not connect the deployment of Rajah Humabon to the deployment of this maritime vessel of China,” Eduardo Batac, spokesman of the Philippines’ department of defense, said in a press briefing on Friday. “It’s part of routine patrols that are being conducted by the Navy.”

As the Philippines and Vietnam move ahead with oil and gas project in the South China Sea against China’s wishes, the tension in one of the worlds busiest shipping lanes have also increased, the official Xinhua news agency reported.

“We are very concerned about the defensive markers being placed by China on three reefs in the South China Sea, features that are clearly ours,” Philippine Foreign Secretary Albert F. del Rosario told reporters in Canberra on Thursday.

Chinese ships have rammed survey vessels operated by PetroVietnam twice in the past month, according to Vietnam’s foreign ministry.