China accused the United States of trying to "stir up trouble" on Monday by sending two U.S. guided-missile destroyers near disputed South China Sea islands.
The two warships sailed near the Beijing-claimed Spratly Islands earlier Monday as part of what Washington calls "freedom of navigation operations," Chinese foreign ministry spokeswoman Hua Chunying told a daily press briefing.
The U.S. is "determined to stir up trouble in the South China Sea, create tension and undermine peace", Hua said.
She urged the U.S. to cease the "provocative actions."
The sail-bys - conducted by USS Spruance and USS Preble - occurred as both sides started crucial trade talks in Beijing this week, seeking to avoid an all-out trade war between the world's two biggest economies.
Beijing asserts nearly all of the South China Sea as its territorial waters, while Taiwan, the Philippines, Brunei, Malaysia and Vietnam all claim parts.
The U.S. and its allies periodically send planes and warships near South China Sea islands and reefs claimed by Beijing to signal their right under international law to pass through the waters, invariably angering China.
In mid-January, U.S. and British warships conducted their first joint military exercises in the South China Sea since Beijing began building bases and air strips on islands.
Another U.S. warship, USS McCampbell, sailed within 12 nautical miles (22 kilometers) of the Paracel Islands chain - north of the Spratly Islands - on Jan. 7 during a previous round of trade talks between the two countries.
Just a day after that operation, Chinese state broadcaster CCTV reported that Beijing had deployed an anti-ship ballistic missile known as the DF-26 - with a range of 3,000 to 4,000 kilometers - to the country's northwest.