The video may seem too simple, too understated to mark a serious international incident in the South China Sea: a quick clip of a diver using a knife to cut a section of rope underwater.

But that diver was with the Philippine coast guard, and the rope was part of a sea barrier placed by Chinese forces to keep Philippine boats away from an area they had a legal right to fish in. In that moment, the Philippines took one of the most forceful steps yet in contesting China’s unrelenting territorial claims ever closer to the Philippine Islands.

"The barrier posed a hazard to navigation, a clear violation of international law,” the Philippines said in a statement, adding that the action had come on direct orders from President Ferdinand Marcos Jr.