WASHINGTON – A U.S. Navy warship on Friday passed through waters claimed by China near disputed islands in the South China Sea, the Defense Department said, drawing Chinese condemnation.

A department spokesman, Navy Cmdr. Gary Ross, said the destroyer ship USS Decatur conducted the transit operation near the Paracel Islands. He said it was done “in a routine, lawful manner without ship escorts and without incident.”

A Chinese defense ministry statement called it “a gravely illegal act” and “intentionally provocative.” The Chinese navy sent a guided missile destroyer and an escort vessel that “spotted and verified the American ships and warned them to leave,” the statement said.

Ross said there was just one U.S. vessel involved.

The Paracels, a group of islands and reefs, are occupied by China but are also claimed by Vietnam and Taiwan.

Ross said the ship passed within an “excessive” claim of territorial waters by China between two land features, although it did not go within 12 nautical miles of them.

He did not specify where in the Paracels the ship sailed.

The U.S. Navy has now conducted four freedom-of-navigation operations in the past year in the South China Sea, where China has reclaimed land on a massive scale to assert its claim to disputed features – mostly in the Spratly islands that lie further south.

China has looked dimly upon the U.S. operations, which it views as meddling in waters where the U.S. does not have territorial claims. Friday’s operation comes a day after the leader of the Philippines, one of the six governments with claims in the South China Sea, announced during a visit to Beijing his nation’s “separation” from the United States, as it seeks to deepen ties with China.

Ross said the operation was unrelated to any such event.