Specifically, the U.S. Navy destroyer sailed near Triton Island, a China-held island in the disputed Paracel group, also claimed by Taiwan and Vietnam.
The 12-mile line is the internationally recognized distance that separates the shores of a sovereign nation from global waters.
Those efforts had "not worked out", Trump tweeted on June 20, adding, "At least I know China tried!"
The Xisha Islands are an inherent part of the Chinese territory, Lu said, noting that in accordance with the Law of the People's Republic of China on the Territorial Sea and the Contiguous Zone, the Chinese government promulgated the baseline of the territorial sea off the Xisha Islands in 1996. "All operations are conducted in accordance with worldwide law and demonstrate that the United States will fly, sail, and operate wherever global law allows", the department's representative said.
China has rapidly built reefs in the area into artificial islands capable of hosting military planes.
For his part, Presidential Spokesperson Ernesto C. Abella told reporters in a news conference on Friday that Manila will follow Mr. Duterte's "non-combative and non-adversarial" approach in fixing issues with China.
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"I think that that was something that we did in the first week or two, I can't remember exactly when we stopped it", Myers said . Monday's White House press briefing was held off-camera, continuing a recent trend that doesn't show signs of stopping.
Duterte, who seeks softened ties with Chinese President Xi Jinping, has said it is not time yet to raise the arbitral ruling reaffirming Philippines' claim that China has no basis to lay claim on disputed waters.
The US Navy sent the destroyer USS Stethem within 22 kilometres of Triton Island on Sunday, said the official, who wasn't authorised to speak publicly. Sailing within those 12 miles is meant to show that the United States does not recognise territorial claims there. During then-Secretary of State nominee Rex Tillerson's confirmation hearing in front of the Senate Armed Forces Committee, he suggested that the USA should use military force to restrict China's access to the islands. The White House, in both the Obama and Trump administrations, has seen the militarization of the South China Sea as a threat to stability in the resource-rich region, where ships from numerous countries have long fished. "That is true in the South China Sea as in other places around the globe".
In May the USS Dewey, another destroyer, sailed six miles from one of China's man-made islands in the South China Sea. China has now built four additional shelters at Fiery Cross. In February, AMTI identified eight hardened shelters with retractable roofs at each of the Big Three, which Reuters had earlier reported would house missile launchers.
Two more domes are also being built at Mischief Reef, it said.
Further positive signs had followed, including an agreement in May on exporting United States beef and natural gas to China.