A Chinese warship collided with one of its own coast guard vessels while chasing Philippine boats earlier this week in the highly contested South China Sea, the latest incident that underscores growing volatility in one of the world’s most strategically vital waterways.

A Philippine official said Chinese coast guard ships chased and staged dangerous blocking maneuvers on Monday against the Philippine coast guard and fishing vessels in the Scarborough Shoal.

Video released by the Philippine Coast Guard shows the China Coast Guard ship charging after the BRP Suluan at high speed, only to veer straight into the path of the much larger PLA Navy ship. The result was a deafening crash and a mangled bow that left the coast guard ship “unseaworthy".