MANILA - President Rodrigo Duterte on Friday hit the United States and former President Benigno Aquino III for their supposed failure to stop China’s militarization of the disputed South China Sea.

This amid reports that Beijing has installed missiles on three artificial islands in the Spratlys located in an area being claimed by Manila.

While it did not call out China for its heavily criticized fortification in the contested waters, Duterte said only the United States had the capability to stop Chinese island-building activities.

“The only country who could have stopped the Chinese… was America,” Duterte said in a speech in Davao City.

“Hindi puwede 'yung Navy natin (cannot handle it), it could have resulted in [a] massacre and I was not [yet] the president [then].”

The US, a long-standing Philippine defense ally, warned China of its reported military buildup. It has repeatedly called for a peaceful resolution of the South China Sea dispute, citing the need to protect freedom of navigation in the vital waterway.

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Duterte made these statements without directly citing the reported Chinese missiles.

But making reference to the maritime dispute, the President said the US government and his predecessor, Benigno Aquino III, had made some missteps in dealing with China.

It was the Aquino administration that hailed China to a United Nations-backed arbitral tribunal in 2013. But the tribunal released its ruling in favor of the Philippines in July 2016, 12 days after Duterte took his oath as President.

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The ruling invalidated China’s massive claim to the sea, dealing a blow to its maritime ambitions. Beijing has ignored the ruling, ramping up its militarization and island-building activities instead.

“Aquino filed an arbitration case, we won. He was still there, bakit hindi niya ginawa kung 'yan talaga ang gusto ‘yan silang mga yellows (why didn't he do it if that's what the yellows really want)?” Duterte said, seemingly forgetting he was already President and Aquino was out when the ruling was handed down.

“Nanalo kayo nandiyan pa si Aquino… bakit di niyo pinuntahan at sinita (You won the case when Aquino was still there. Why didn't you go (to the islands) and call out the Chinese?)” he said.

Duterte has refused to flaunt the arbitration victory against China in pursuit of better economic ties with one of the world's largest economies. He, however, said he would raise this at the proper time.

The Chinese army installed anti-ship and air-to-air defenses on outposts also claimed by Vietnam and the Philippines over the last 30 days, American television network CNBC reported Wednesday, citing sources close to US intelligence.

The new Chinese missiles were reportedly deployed on Fiery Cross Reef, Subi Reef and Mischief Reef, according to CNBC.

They are all in the Spratlys archipelago located in waters south of mainland China between Vietnam and the Philippines.

Malacañang has downplayed the missile deployment, saying “we are confident that those missiles are not directed at us.”