Manila accused Beijing of again damaging a civilian resupply vessel and injuring personnel with water cannons on Saturday near a remote Philippine military outpost in the disputed South China Sea.

The Philippine military said China Coast Guard vessels had severely damaged the Unaizah May 4 (UM4) resupply ship as it headed for the military base that sits grounded atop the flashpoint Second Thomas Shoal, which is also claimed by China.

"China Coast Guard and Chinese Maritime Militia vessels once again harassed, blocked, deployed water cannons, and executed dangerous maneuvers against (a routine rotation and resupply) mission that led to significant damage to the supply vessel and caused injury to personnel," the Philippine government said in a statement, adding that injured crew had later been given medical treatment aboard one of the country's coast guard vessels.

Video released by the Philippine military showed two China Coast Guard ships simultaneously firing high-powered water cannons at the UM4 after a separate video clip showed one of the Chinese vessels earlier performing a “reverse blocking maneuver” against the resupply vessel, narrowly avoiding a collision.

In what was believed to be the first move of its kind in the Second Thomas Shoal, the Philippine military also released video showing what it said were Chinese government-linked maritime militia vessels installing floating barriers “to prevent further entry of any vessels in the shoal.”

China Coast Guard and maritime militia vessels have repeatedly sought to prevent resupply missions from reaching Philippine troops stationed on the rusting BRP Sierra Madres, a World War II-era ship that was intentionally grounded on the shoal in 1999.

Saturday’s nearly hourlong encounter was the latest in a string of incidents — including collisions and the use of water cannons — involving the two countries in the strategic waterway, which is almost entirely claimed by China.

Earlier this month, the UM4 was sprayed with high-pressure water cannons by China Coast Guard ships, shattering the boat’s windshield and mildly injuring an admiral and four sailors aboard the vessel.

"The systematic and consistent manner in which (China) continues to carry out these illegal and irresponsible actions belies its hollow claims to peace, dialogue, and adherence to international law," the Philippine government said Saturday.

Later Saturday, a Chinese Foreign Ministry spokesperson alleged that the Philippine boat had been attempting "to send construction materials to the illegally grounded military vessel" at Second Thomas Shoal "for its repair and reinforcement."

"If the Philippines insists on going its own way, China will continue to adopt resolute measures to safeguard its territorial sovereignty and maritime rights and interests," the spokesperson said. "The Philippines should be prepared to bear all potential consequences."

An statement released earlier in the day by the China Coast Guard, meanwhile, claimed that the Philippines had broken a promise to remove the grounded vessel by sending two coast guard ships and a supply ship into the waters near Second Thomas Shoal, 18 days after it last supplied the outpost.

A vessel identified by the Armed Forces of the Philippines as a Chinese rigid-hull inflatable boat installs a floating barrier during a Philippine supply mission near Second Thomas Shoal in the disputed South China Sea on Saturday.
A vessel identified by the Armed Forces of the Philippines as a Chinese rigid-hull inflatable boat installs a floating barrier during a Philippine supply mission near Second Thomas Shoal in the disputed South China Sea on Saturday. | ARMED FORCES OF THE PHILIPPINES / VIA AFP-JIJI

Manila has denied that such a promise was made, and Beijing has not said who the deal was made with or when it took place.

China Coast Guard spokesperson Gan Yu said the latest move highlighted that the Philippines “is bent on deliberately undermining peace and stability in the South China Sea.” The Chinese side, Gan said, had “handled the matter in a reasonable, lawful and professional manner” — while also delivering an ominous warning.

On Saturday morning, the Philippine Armed Forces also released video clips showing a Philippine Coast Guard vessel that was escorting the UM4 “impeded and encircled” by Chinese coast guard and maritime militia vessels.

Philippine Coast Guard Commodore Jay Tarriela said in a post on the X social media site that the encircled ship had been “isolated from the resupply boat due to the irresponsible and provocative behavior of the Chinese maritime forces, who have shown a disregard for the Convention on the International Regulations for Preventing Collisions at Sea.”

Ultimately, the resupply mission appeared to be at least partially successful, with video and photos released by the Philippine military showing navy personnel and essential cargo being transferred from the UM4 to the base.

Tensions between Manila and Beijing near the Second Thomas Shoal have soared in recent months. From Chinese laser pointers blinding Philippine sailors to several collisions at sea, the row in the South China Sea has threatened to escalate into a larger crisis, including one that could draw in the U.S., Manila’s defense treaty ally.

Under its so-called nine dash line, Beijing maintains a claim to some 90% of the South China Sea, through which trillions of dollars in trade flow every year, overlapping with the exclusive economic zones of Vietnam, Malaysia, Brunei, Indonesia and the Philippines.

Beijing, meanwhile, has hardened its position on the South China Sea, which flies in the face of a July 2016 ruling by the Permanent Court of Arbitration in The Hague invalidating most of its claims in the waterway, prompting pushback from other claimants.

Under President Ferdinand Marcos Jr. the Philippines, in particular, has repeatedly publicized China’s tactics in the strategic waterway, which is also home to rich fishing grounds and oil reserves.