Chinese coast guard ships hit a Philippine supply boat with water cannons Saturday in the latest confrontation near a disputed shoal in the South China Sea, causing injuries to its navy crew members and heavy damage to the wooden vessel, Philippine officials said.

The United States and Japan immediately expressed their support to the Philippines, as well as alarm over Chinese forces’ aggression off the Second Thomas Shoal, which has been the scene of repeated confrontations between Chinese and Philippine vessels over the past year.

The far-flung shoal has been occupied by a small contingent of Philippine navy and marines on a marooned warship since 1999, but has been surrounded by Chinese coast guard and suspected militia vessels in an increasingly tense territorial standoff. It’s the second time the Philippine boat Unaizah May 4 has been damaged by the Chinese coast guard’s water cannon assault in March alone.

The repeated high-seas confrontations have sparked fears they could degenerate into a larger conflict that could bring China and the United States into a collision.