The U.S. slammed China for “reckless disregard” and provocative action after Chinese coast guard boats shot water cannons at Philippine ships and collided with a vessel in the South China Sea over the weekend.

State Department spokesperson Matthew Miller said Chinese boats also deployed acoustic devices, or sound cannons, which can employ extremely loud sounds over a distance to incapacitate a target, to drive away Philippine boats.

China “interfered in lawful Philippine maritime operations and in Philippine vessels’ exercise of high seas freedom of navigation,” Miller said Sunday in a statement. “Obstructing supply lines to this longstanding outpost and interfering with lawful Philippines maritime operations undermines regional stability.”

“These actions reflect not only reckless disregard for the safety and livelihoods of Filipinos, but also for international law,” he added.

Chinese and Philippine boats engaged one other Saturday near the disputed area of Scarborough Shoal, where China shot high-pressure water cannons at three Philippine fisheries vessels, damaging communication and other equipment. Beijing was also accused of using a sound cannon in the incident.

On Sunday, China shot more water cannons at Philippine supply boats near the disputed area of Second Thomas Shoal and severely damaged two of them.

Resupply boats that approached to help were also shot at with water cannons, and one of them was rammed and grounded near an outpost. Filipino naval ships have been running supplies to the grounded vessel.

Chinese Foreign Ministry spokesperson Mao Ning blamed the Philippines for intruding on Beijing’s sovereign territory and accused Manila of reinforcing the grounded vessel in an attempt to occupy the area.

“We once again urge the Philippines to stop infringing on China’s sovereignty and making provocative moves, stop groundlessly attacking and smearing China, and avoid undermining peace and stability in the South China Sea,” Mao Ning said in a Monday press conference.

Philippines President Bongbong Marcos said the “illegal presence in our waters and dangerous actions against our citizens is an outright and blatant violation of international law and the rules-based international order.”

“The aggression and provocations perpetrated by the China Coast Guard and their Chinese Maritime Militia against our vessels and personnel over the weekend have only further steeled our determination to defend and protect our nation’s sovereignty, sovereign rights, and jurisdiction in the West Philippine Sea,” Marcos wrote on X, formerly Twitter.

China has claimed swaths of the South China Sea as its own, which has led to disputes with the Philippines, Vietnam and other Indo-Pacific nations.

The Permanent Court of Arbitration in The Hague in 2016 ruled China’s claims over much of the South China Sea are not lawful. China has disregarded the 2016 ruling and continues to lay claim to around 90 percent of the South China Sea, resulting in continued clashes with the Philippines. Earlier this year, China also shined high-powered lasers on Filipino boats.