MANILA — America's increased military air activity within Philippine airspace should not be a cause for alarm, retired Supreme Court Associate Justice Antonio Carpio said on Tuesday.

He said the recent flights of US military aircraft were "vastly different" to the Chinese presence in Philippine waters.

"The Chinese are present in the West Philippine Sea because they claimed the West Philippine Sea as their own," Carpio told ANC's "Headstart".

"The Americans are in the West Philippine Sea not to claim the West Philippine Sea for their own but to assert that there is freedom of navigation and overflight in the West Philippine Sea in accordance with UNCLOS (United Nations Convention for the Law of the Sea)," he added.

For Carpio, the US is "telling the world" that the West Philippine Sea is the exclusive economic zone of the Philippines.

"So, in effect, whenever the US and its allies sail in the West Philippine Sea, they actually enforce the arbitral award," he said. "On the other hand, when China sails in the West Philippine Sea, they oppose the arbitral award."

• Imee questions increased US air activity within PH airspace

House Deputy Minority Leader France Castro wants the lower chamber to look into the flights of US armed forces in the country.

The ACT party-list lawmaker believed this could be connected to the recent swarming of Chinese vessels in the West Philippine Sea.

Sen. Imee Marcos has also said "too little is known about the ongoing US military activity".

The Philippine Coast Guard has vowed to continue to expose China's incursions.

The military recently reported spotting 48 Chinese fishing vessels swarming Iroquois Reef and 5 Chinese Coast Guard and People's Liberation Army Navy vessels near Sabina Shoal.

In 2016, the Permanent Court of Arbitration in The Hague ruled in favor of Manila and junked Beijing's claim to about 90 percent of the South China Sea.

However, Beijing has been accused of militarizing the marine resources- and energy-rich waters, a major international trade route.

• Pagpasok ng mga barko ng China, eroplano ng US pinuna ng ilang mambabatas

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