President Rodrigo Duterte vowed on Thursday to confront China if it starts to siphon the resources out in the South China Sea.

Duterte, in a series of interviews by some news agencies, said that he would bring up the ruling of the Permanent Court of Arbitration (PCA) "during my time."

He said he could not just allow to finish his term without bringing the PCA award on the Philippines invalidating China's nine-dash line in the disputed waters.

But Duterte, who embarked on a state visit to China in October, did not raise the international tribunal ruling on the matter during his meeting with Chinese President Xi Jinping.

Asked of the specific circumstance when he would bring up the PCA ruling, he said, "when the minerals (in the South China Sea) are already being siphoned out."

He said if this happens, he would tell China, "I thought we're friends. Where's the title? Don't you think it will be better to talk now?"

Duterte hailed the decision of his predecessor, Benigno Aquino III, in questioning before the United Nations Arbitral Tribunal China's nine-dash line, which practically covers the entire South China Sea, including those within the 200-nautical miles exclusive economic zone of other countries, like the Philippines.

"It was a good move of President Aquino," he said.

Duterte said if the United States would want to go to war with China on the South China Sea, it could go ahead.

The Philippines, which has a Mutual Defense Treaty with the US, would only join America on its war with China if after calling for a command conference with the security and military officials Manila would support it, he added.

He wondered why the US did not act when China was still doing reclamation activities in the South China Sea considering that it has the capability.

China has built artificial lands in the disputed waters despite opposition of the claimant countries.

Meanwhile, Duterte admitted that he was "still trying to figure out" what he would do with the Visiting Forces Agreement with the US because of the opposition of certain quarters not to abrogate the deal. He earlier said he wants to abrogate the VFA.

He said he was still waiting for the assumption to office of US President-elect Donald Trump, whom he described as "kind."

Duterte earlier called up Trump to congratulate him on his victory. Celerina Monte/DMS