China has sent fighter jets and a naval flotilla to the Paracel Islands in the South China Seas after a US warship was deliberately routed through the area.
The disputed islands lie south of China, between Vietnam and the Phillipines.
China has called the presence of the USS Stetham close to Triton Island:
"A serious political and military provocation".
The US has repeatedly warned China over its occupation of the islands and what its described as their "aggresive reclamation".
Both Vietnam and Taiwan also claim the Paracel islands, while the Philippines, Indonesia, Malaysia and Brunei have claimed jurisdiction over other nearby islands.
The Chinese President Xi Jinping telephoned the US President Donald Trump just hours after the warship passed the island but the White House would not confirm whether they had discussed the issue.
A US government statement said the USS Stetham sailed within 12 miles of Triton Island conducting 'freedom of navigation' exercises.
The area has significant strategic importance.
Busy shipping lanes pass through the islands and there are thought to be large oil and gas reserves as well as traditional fishing grounds.