The incident happened Saturday as the Philippine Coast Guard escorted charter boats carrying food, water, fuel and other supplies for Filipino military personnel stationed at Second Thomas Shoal in the Spratly Islands.
Beijing claims almost all of the South China Sea, through which trillions of dollars in trade passes annually, and has ignored a 2016 international court ruling that its assertion has no legal basis.
The Philippine military and coast guard have accused the China Coast Guard of breaking international law in blocking and firing water cannon at the re-supply mission, which prevented one of the charter boats reaching the shoal.
Another charter boat was successful in unloading its cargo.
China said it had taken “necessary controls” against Philippines boats that had “illegally” entered its waters.
“Our Secretary of Foreign Affairs summoned Ambassador Huang today and gave him a note verbale including pictures, video about what happened and we are awaiting their reply,” Marcos told reporters.
“The position of China, of course, is they say ‘this is ours so we are defending it’ and we, for our part, are saying ‘no, we own it so we are defending it’. So that becomes a grey area that we are discussing.”
The US State Department on Sunday condemned the Chinese actions, saying they were carried out by the coast guard and “maritime militia”, and that they directly threatened regional peace and stability.
Britain, Australia, Canada and the European Union also criticised Beijing’s actions.
Second Thomas Shoal is about 200 kilometres (124 miles) from the Philippine island of Palawan and more than 1,000 kilometres from China’s nearest major landmass of Hainan island.
China’s coast guard and navy vessels routinely block or shadow Philippine ships patrolling the contested waters, Manila says.
The Philippines has issued more than 400 diplomatic protests to Beijing since 2020 over its “illegal activities” in the South China Sea, the foreign ministry said.
“For the record, we will never abandon Ayungin Shoal. We are committed to Ayungin Shoal,” National Security Council spokesman Jonathan Malaya told reporters Monday, using the Philippine name for Second Thomas Shoal in the Spratly Islands.
Sovereignty claim unlawful
Saturday’s incident was the first time since November 2021 that the Chinese coast guard had used water cannon against a Philippine resupply mission to Second Thomas Shoal.
“The Philippines condemns in the strongest terms the latest incident of harassment perpetrated by China Coast Guard, People’s Liberation Army Navy and Chinese maritime militia vessels,” said the National Task Force for the West Philippine Sea, which includes representatives of various government agencies.
“As a low tide elevation, Ayungin shoal can neither be the subject of a sovereignty claim nor is it capable of appropriation under international law,” the task force said in a statement.
The Philippines insists the Second Thomas Shoal is part of its exclusive economic zone.
Manila and Beijing have a long history of maritime disputes over the South China Sea.
However former Philippine president Rodrigo Duterte, who was in power from 2016 to 2022, was reluctant to criticise his more powerful neighbour as he sought closer ties with Beijing in the hope of attracting investment.
Marcos has insisted since succeeding Duterte that he will not let China trample on his country’s maritime rights.
He has gravitated towards the United States, seeking to strengthen defence ties with the Philippines’ former colonial ruler and longtime ally.
