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MANILA — The Chinese coast guard committed a "clear violation of international law" when its vessels blocked and fired water cannons at Filipino boats on their way to Ayungin Shoal in the West Philippine Sea, former Foreign Affairs Sec. Albert del Rosario said Thursday.

Del Rosario's statement came hours after National Security Adviser Hermogenes Esperon Jr. confirmed that Chinese Coast Guard vessels hindered and used water cannons against Filipino supply boats that were transporting food supplies to military personnel at the BRP Sierra Madre based in Ayungin Shoal on Tuesday, Nov. 16.

• Chinese Coast Guard use water cannon on PH supply boats

"It is an affront to Philippine sovereign rights over its continental shelf," Del Rosario said.

Manila considers Ayungin Shoal or Second Thomas Shoal, which lies 105 nautical miles (195 km) southwest of the Philippine region of Palawan, as being within its 200-nautical mile the West Philippine Sea, or the country's exclusive economic zone.

It has occupied the shoal since 1999 after intentionally grounding the BRP Sierra Madre on the reef.

Del Rosario said that the UN-backed court ruling that invalidated Beijing's expansive economic claims in the South China Sea adjudicated Ayungin Shoal "as a low tide elevation (lte)."

"Accordingly, the tribunal ruled it unequivocally as part of the Philippine continental shelf which is not subject to territorial claim by any other country. Being not susceptible to a territorial claim by any other country, there can be no territorial dispute on the same," he said.

"Only the Philippines has the exclusive sovereign rights over its continental shelf including Ayungin Shoal."

Meanwhile, China, which has since ignored the ruling and ramped up militarization and island-building activities in the waters, said Filipino boats in the recent incident with its coast guard were "trespassing into Chinese waters."

“Chinese coast guard vessels performed official duties in accordance with law and upheld China's territorial sovereignty and maritime order," Chinese Foreign Ministry spokesperson Zhao Lijian said in a press conference in Beijing.

• Beijing claims PH supply boats 'trespassed in Chinese waters' in Ayungin incident

Manila has diplomatically protested and condemned "in strongest terms" the actions of the Chinese vessels.

Del Rosario, who commended the move to file a diplomatic protest, said the Chinese aggression may have been encouraged or can be traced back by past diplomatic or foreign policy mistakes by the current administration.

Manila earlier chose to have bilateral talks with Beijing to settle the two countries' maritime dispute in the South China Sea, instead of taking a multilateral approach which local and international experts and officials were calling for.

• Robredo backs multilateral talks to equalize PH-China footing in sea dispute

"We focused principally on bilateral diplomacy while neglecting the other tools in our toolbox which would have enabled us to move the tribunal’s ruling to the next level," he said.

"Ayungin Shoal is ours. The (UN-backed) tribunal agreed with us more than five years ago."

MUTUAL DEFENSE TREATY WITH US

Del Rosario, who was foreign affairs chief when Manila lodged the arbitration case against Beijing in 2013, said the Philippines should consider Ayungin Shoal "as a proper subject of the Mutual Defense Treaty" with the United States.

He also called on government to consider joint patrols in the West Philippine Sea with security allies.

The Philippines and the United States on Wednesday unequivocally affirmed the 2016 arbitral award that invalidated China’s expansive claims over the South China Sea.

Both countries reiterated the application of the Mutual Defense Treaty on an armed attack on Philippine armed forces, public vessels, or aircraft in the hotly-contested waters.

• PH, US: 2016 S. China Sea ruling binding to China

Incumbent Foreign Affairs Sec. Teodoro Locsin, Jr. said he also reminded Chinese Ambassador to the Philippines Huang Xilian that public vessels are covered by the 70-year-old pact, as he conveyed Filipino condemnation and protest of the Ayungin Shoal incident.

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