An aerial view of Itu Aba, which the Taiwanese call Taiping, in the South China Sea on November 29. REUTERS/Fabian Hamacher SYDNEY — The US is ready to confront China should it continue its overreaching maritime claims in the South China Sea, the head of the US Pacific fleet said on Wednesday, comments that threaten to escalate tensions between the two global rivals.

China claims most of the resource-rich South China Sea through which about $5 trillion in ship-borne trade passes every year. Its neighbors Brunei, Malaysia, the Philippines, Taiwan, and Vietnam also have claims.

The US has called on China to respect the findings of arbitration court in The Hague earlier this year that invalidated its vast territorial claims in the strategic waterway.

But Beijing continues to act in an "aggressive" manner, to which the US stands ready to respond, Adm. Harry Harris, head of the US Pacific Command, said in a speech in Sydney.

"We will not allow a shared domain to be closed down unilaterally no matter how many bases are built on artificial features in the South China Sea," he said. "We will cooperate when we can, but we will be ready to confront when we must."

The comments threaten to stoke tensions between the US and China, already heightened by President-elect Donald Trump's decision to accept a telephone call from Taiwan's president on December 2 that prompted a diplomatic protest from Beijing.

The US estimates Beijing has added more than 3,200 acres of land on seven features in the South China Sea over the past three years, building runways, ports, aircraft hangars, and communications equipment.

In response, the US has conducted a series of freedom-of-navigation operations in the South China Sea, the latest of which came in October.

The patrols have angered Beijing, with a senior Chinese official in July warning the practice may end in "disaster."

Harris said it was a decision for the Australian government whether the US ally should undertake its own freedom-of-navigation operations, but he said the US would continue with the practice.

"The US fought its first war following our independence to ensure freedom of navigation," Harris said. "This is an enduring principle and one of the reasons our forces stand ready to fight tonight."

(Editing by Lincoln Feast)