The head of the U.S. Indo-Pacific Command said on Tuesday that he was �very, very concerned� about China�s aggression toward Philippine forces near disputed islands in the South China Sea.

The Chinese coast guard has repeatedly clashed with Philippine patrol vessels near the Philippines-occupied Second Thomas Shoal. Last month, several Filipino seamen were injured when a Chinese vessel sideswiped a smaller Philippine vessel and another two Chinese coast guard ships used high-pressure water spray to shatter the Philippine vessel�s windscreen.

Asked if the submerged reef in the Spratly Islands was the most dangerous flash point in his area of command, U.S. Adm. John Aquilino told a forum at the Lowy Institute, a Sydney-based international policy think tank: �I�m very concerned about what�s happening at the Second Thomas Shoal.�

�I�m very, very concerned about the direction it�s going,� Aquilino said. �These actions are dangerous, illegal and they are destabilizing the region.�

�What�s next and how far are they willing to go in that area?� Aquilino asked.

The United States, Japan, the Philippines and Australia held their first four-way joint exercises in Philippine waters in the South China Sea on Sunday, which they said were intended to uphold freedom of navigation and overflight in a region contested by China.

Aquilino said the joint exercise demonstrated the nations� ability to operate safely, effectively and lawfully in the region.

�Those types of events and things are exactly what we need to do to demonstrate that strength amongst the like-minded allies and partners and that we will continue to operate anywhere that international law allows,� Aquilino said.

China�s military said Sunday that it had conducted air and sea patrols and that all activities that �disrupt the South China Sea� are under control, an apparent response to naval exercises by the U.S. and its allies.

(AP)