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 E. Marcos Jr.
Since he took office in June 2022, Mr. Marcos has signaled wanting a more muscular foreign policy approach toward China. But until now, those actions were confined mostly to rhetoric, deepening alliances with the United States and other countries, and releasing videos of aggressive activities undertaken by the Chinese Coast Guard against Philippine vessels.
The surprise this time was that the action was being taken by Manila. It has left little doubt that the Philippines is offering more forceful resistance to China’s territorial designs.
While the Biden administration is likely to see that as good news, apprehension is rising in the region about how China might counter that resistance, and whether there could be a risk of sparking a direct military clash among China and the Philippines and its allies, including the United States Navy fleet patrolling the region.
After the rope was cut and the Philippines lifted the anchor that kept it in place, China removed the barrier. On Tuesday, a spokesman for China’s foreign ministry brusquely dismissed the Philippine statement. “We advise the Philippines not to cause provocation and cause trouble,” he said.
Song Zhongping, a commentator in Beijing who is a former military officer, said the Philippines was emboldened to cut the barrier “because the United States continues to encourage the Philippines to confront China in the South China Sea.”
“China must take decisive measures to put an end to the Philippines’ provocation,” Mr. Song said. “We can’t allow the Philippines to commit endless provocations and pose a serious threat to China’s national sovereignty and security.”
China claims 90 percent of the South China Sea, some of it thousands of miles from the mainland and in waters surrounding Vietnam, Malaysia, Brunei, Indonesia and the Philippines. In the past decade or so, China has asserted ever greater control over these waters, using two island chains called the Paracels and the Spratlys to expand its military footprint by building and fortifying outposts and airstrips.
These actions have alarmed much of Asia and the United States, which says it has a vested interest in maintaining freedom of navigation in one of the world’s busiest shipping lanes. China’s military buildup, and increasingly aggressive action by its coast guard and maritime militia, have also raised questions about China’s intentions in the region and its willingness to comply with international law and norms.
The tensions are particularly pronounced in the Philippines, where fishermen have been blocked by Chinese vessels from fishing, and Manila has been prevented from fully exploring oil and gas deposits within an area that an international tribunal in The Hague ruled in 2016 to be part of the Philippines’ exclusive economic zone.
Many analysts say China is likely to stop short of taking any military action against the Philippines, a treaty ally of the United States, for fear of being embroiled in a broader conflict with Washington and other U.S. allies in the region. In August, the American defense secretary, Lloyd Austin, reaffirmed that a mutual defense treaty with the United States “extends to Philippine public vessels, aircraft and armed forces — to include those of its Coast Guard — in the Pacific, including in the South China Sea.”
“If the U.S. has to engage in a military confrontation with China in the South China Sea, you can’t expect Australia and Japan, for example, to just sit there and idle about while their American allies are fighting the Chinese,” said Collin Koh, a senior fellow at the Institute of Defense and Strategic Studies in Singapore. “They will be drawn into it somehow. So this is something that I believe any good Chinese planner will have to consider.”
Mr. Koh said he expects China to ramp up its presence in the South China Sea, perhaps by sending more vessels around disputed areas like Thitu Island and the Second Thomas Shoal to prevent Filipino fishermen from operating freely and to block maritime law enforcement vessels.
Bilahari Kausikan, a former ambassador at large with Singapore’s Ministry of Foreign Affairs, said he believes “Beijing has enough problems at home without wanting to add to them by picking a confrontation with the U.S. as well.”
Mr. Kausikan said “the risk of conflict would be higher” if the Philippines had not removed the barrier, “because then the Chinese would be tempted to push the boundaries even further.”
But Leonardo Cuaresma, president of the New Masinloc Fishermen’s Association in the Philippines, said that in the municipality where the barrier was cut, he was nervous about how China could react.
“Here in Masinloc, it’s natural to feel fear because should there be a conflict, we will be the first one to feel it,” Mr. Cuaresma said. “It’s difficult, because we don’t know if there will be a war or what. We are anxious.”
Mr. Cuaresma said he and his peers have not been able to fish in the Scarborough Shoal for years because of China. “The moment we get near the entrance of the shoal, they would immediately block us,” he said. “Their smaller boats would sail beside us and tell us: ‘Go away, Filipino.’”
Alongside the high emotions, there is still anxiety in Manila about how to deal with China.
Koko Pimentel, the Philippine Senate Minority Leader, told a Senate hearing that he agreed with the Marcos government’s decision to remove the Chinese barrier. But later, in a text message to a New York Times reporter, he offered a cautious addition: “We should avoid conflict as much as possible. Do everything through dialogue and diplomacy. Differing positions are a fact of life, and we should be able to navigate through life with this reality.”
Antonio Carpio, a former Supreme Court Senior Associate Justice in the Philippines and an expert on the South China Sea, said the Philippines was just mirroring what Malaysia and Indonesia did recently when both countries sent their ships to survey in disputed waters despite threats from China.
“If you assert your right and you stand your ground, well, China will not do anything,” he added.
Mr. Carpio said that, more broadly, the international community must pay attention to what is happening in the South China Sea because “what is at stake in Ukraine and in the South China Sea are exactly the same.”
“All nations must oppose this, because this is not just a matter of the Philippines, it’s about the future of the world,” he said. “If the U.N. Charter, which outlawed the wars of aggression, is overturned, then only nuclear powers will be able to settle disputes according to their dictates. It will be ‘might is right’ again.”
Camille Elemia and Joy Dong contributed reporting.