China’s Defense Ministry on Sunday warned the Philippines to halt actions that “could escalate the situation” in the disputed South China Sea, a day after Manila accused Beijing of severely damaging a vessel and injuring its crew with water cannons during a resupply mission to a military outpost.
On Saturday, the Philippine military said China Coast Guard vessels and Chinese government-linked maritime militia vessels had “once again harassed, blocked, deployed water cannons, and executed dangerous maneuvers” against vessels taking part in the mission to the flashpoint Second Thomas Shoal, which is also claimed by China.
Philippine authorities said Chinese actions had “led to significant damage” and “caused injury to personnel” aboard the Unaizah May 4 (UM4), a civilian boat hired to resupply the military base atop a grounded World War II-era warship in the shoal.
The severity of the injuries sustained was not clear, but the crew were later given medical treatment aboard one of the country's coast guard vessels, according to the Philippine side.
In a statement Sunday, the Chinese Defense Ministry alleged that the Philippine mission showed that it had “gone back on its word, betrayed its promise and attempted to consolidate the illegal ‘grounding’ of a warship on Ren'ai Reef into a permanent facility.”
Ren’ai Reef is the Chinese name for Second Thomas Shoal.
“China will never sit idly by and ignore this,” Defense Ministry spokesman Wu Qian said in a statement. “We are warning the Philippines to stop making any remarks that may lead to the intensification of conflicts and escalate the situation, and stop all infringements and provocations.
“If the Philippines repeatedly challenges China's bottom line, China will continue to take resolute and decisive measures to firmly safeguard its territorial sovereignty and maritime rights and interests,” the statement added.
Video released by the Philippine military showed two China Coast Guard ships simultaneously firing high-powered water cannons at the UM4 on Saturday, after a separate video clip released earlier in the day showed one of the Chinese vessels performing a “reverse blocking maneuver” against the resupply vessel, narrowly avoiding a collision.
Manila has characterized the nearly hourlong standoff — the latest in a string of tense encounters between the two sides in the South China Sea — as "irresponsible and provocative."
The waters surrounding Second Thomas Shoal, in particular, have seen a number of incidents, with China Coast Guard and maritime militia vessels repeatedly seeking to prevent resupply missions from reaching Philippine troops stationed on the rusting BRP Sierra Madre warship, which was intentionally grounded on the shoal in 1999 to reinforce Manila’s territorial claims to the area.
Manila has pledged to conduct monthly resupply missions to troops stationed on the base, missions that China suspects include the transport of materials intended to fortify the rusting warship, which Philippine defense officials have conceded is rapidly deteriorating after years of enduring the South China Sea climate.

China has claimed that the Philippines broke a promise to remove the grounded vessel — something Manila has denied. Beijing has not said who the deal was made with or when it took place.
On Saturday, a Chinese Foreign Ministry spokesperson alleged that the Philippine boat had been attempting "to send construction materials to the illegally grounded military vessel ... 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."
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 to the base.
Saturday’s clash was the second in the area this month, with both involving UM4. During an encounter on March 5, China Coast Guard ships sprayed the vessel with high-pressure water cannons, shattering its windshield and mildly injuring an admiral and four sailors.
After the latest clash, the Philippine government lambasted the “systematic and consistent manner in which (China) continues to carry out these illegal and irresponsible actions,” saying the incidents had highlighted “its hollow claims to peace, dialogue, and adherence to international law.”
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.
In Washington, the U.S. State Department on Saturday condemned China’s “dangerous and destabilizing” actions, saying that “the United States stands with its ally” and reiterating its commitment to the 1951 U.S.-Philippines Mutual Defense Treaty, which extends to armed attacks on Philippine armed forces, public vessels, or aircraft — including those of its coast guard — anywhere in the South China Sea.
“(The People’s Republic of China’s) actions prevent normal personnel rotations and deprive Filipino service members at Second Thomas Shoal of necessary provisions,” State Department spokesman Matthew Miller said. “This incident marks only the latest in the PRC’s repeated obstruction of Philippine vessels’ exercise of high seas freedom of navigation and disruption of supply lines to this longstanding outpost.”
Under its so-called nine dash line, Beijing maintains a claim to some 90% of the resource-rich 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.
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