US Defense Secretary Jim Mattis warns China over its actions in South China Sea

US Defense Secretary Jim Mattis (File photo)

US Defense Secretary Jim Mattis warns that Washington will “compete vigorously” if China continues its actions in the South China Sea.

"China's policy in the South China Sea stands in stark contrast to the openness our strategy promises, it calls into question China's broader goals," Mattis said in prepared remarks at the annual Shangri-La Dialogue in Singapore on Friday.

"The US will continue to pursue a constructive, results-oriented relationship with China, cooperating when possible and competing vigorously where we must... of course we recognize any sustainable Indo-Pacific order has a role for China," he added.

His remarks came a few hours after the Pentagon’s Joint Staff director, Gen. Kenneth McKenzie, indirectly threatened China, saying the US military could “take down” Beijing’s artificial islands in the South China Sea.

Vietnam and the Philippines expressed concern last month after China's air force landed bombers on the islands and reefs in the South China Sea as part of a training exercise in the area.

Satellite photographs taken on May 12 showed China had apparently deployed truck-mounted surface-to-air missiles or anti-ship cruise missiles at Woody Island in the disputed sea.

Mattis said that "despite China's claims to the contrary, the placement of these weapon systems is tied directly to military use for the purpose of intimidation and coercion.”

Beijing, which claims sovereignty over the South China Sea and the islands in it, has dismissed the US official’s claims of militarization.

Mattis said the two US Navy warships, which sailed near South China Sea islands on Sunday, were just an "initial response."

The Higgins guided-missile destroyer and the Antietam, a guided-missile cruiser, came within 12 nautical miles of the Paracel Islands.

China has repeatedly warned the United States against sending warships to patrol the South China Sea. Washington claims such operations are meant to protect “freedom of navigation” in the sea, a gateway for trillions of dollars in maritime trade each year.