US Secretary of State Mike Pompeo. Photo: AFP

Secretary of State Mike Pompeo said Monday that the United States would treat Beijing’s pursuit of resources in the dispute-rife South China Sea as illegal, ramping up pressure on another front.

The United States has long rejected Beijing’s sweeping claims in the South China Sea, aligning itself with Vietnam, the Philippines and other US partners in the region.

But Pompeo went further by explicitly siding with Southeast Asian nations, after years of the United States saying that it took no position on the merits of individual disputes.

In line with the 2016 finding of an international tribunal, Pompeo said that the Mischief Reef and Second Thomas Shoal both “fall fully under the Philippines’ sovereign rights and jurisdiction.”

Pompeo also denounced China’s claims on the contested Spratly islands, where China earlier this year announced administrative districts, which would allow Beijing to expand its maritime claims.

The United States as a result now rejects Beijing’s claims in the waters surrounding Vanguard Bank off Vietnam, Lucania Shoals off Malaysia, waters considered in Brunei’s exclusive economic zone and Natuna Besar off Indonesia, Pompeo said.

“Any PRC action to harass other states’ fishing or hydrocarbon development in these waters — or to carry out such activities unilaterally — is unlawful,” Pompeo said.

The statement is the latest assertive step by President Donald Trump’s administration against China, which it has increasingly portrayed as an enemy ahead of November elections.

The United States in recent weeks has slapped visa restrictions on officials over the treatment of the Uighur and Tibetan minorities as well as over Beijing’s clampdown in Hong Kong.

Trump has also harshly criticized China over the coronavirus pandemic.