MANILA - Armed Forces chief of staff Gen. Gilbert Gapay said Tuesday that the situation in the West Philippine Sea and beyond it remains "very tense" because of the activities of China and the United States.

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"China is conducting its own unilateral exercises. It has even fired recently a missile (which) we have lodged a diplomatic protest on," Gapay said in an online forum organized by the Foreign Correspondents Association of the Philippines.

"Here comes (the) United States, displaying a show of force in the area. So, it's very tense," added Gapay.

The Philippine military chief said they have witnessed China's "aggressive actions" over the past years, including land reclamation and deployment of warships and its coast guard.

The US, on the other hand, which advocates freedom of navigation, has been "protecting their interest in maintaining that sea lanes of trade and communications open".

Gapay said the AFP and the Chinese military have open lines of communication to avert any untoward incident, especially since the Philippines continues to assert its sovereignty and interest in the area.

China claims almost the entire South China Sea despite having no legal basis as judged by the Permanent Court of Arbitration in The Hague.

The Philippines, Brunei, Malaysia, Vietnam and Taiwan have competing claims as well in the South China Sea. Manila calls its claimed portion as the West Philippine Sea.

"Within the limits of our capability, we are maintaining presence in the West Philippine Sea. We conduct naval and air patrols everyday in the West Philippine Sea, and it involves seven Navy assets, and no more than 20 aircraft alternately performing air patrols in the area," Gapay said.

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The Philippine Coast Guard is also providing support.

Gapay disclosed that a radar that the country acquired from Japan will be installed on Matinloc gas platform off Palawan after the Department of Energy closed the facility in November last year.

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"We have acquired the Matinloc platform, to be assigned one of the radars coming from Japan to beef up our monitoring capability in the West Philippine Sea," Gapay said.

In late September, Flag Officer In Command Navy Vice Admiral Giovanni Bacordo inspected the Matinloc and Nido gas platforms which are being considered for conversion into military observation posts for Recto Bank and the Malampaya gas field in the West Philippine Sea.