China says it warned and tracked U.S. warship in South China Sea

(CNN)Chinese ships and aircraft warned and tracked a U.S. Navy warship Tuesday as it came close to reefs claimed by China in contested waters in the South China Sea.

Cui Tiankai, the Chinese ambassador to the United States, told CNN's Christiane Amanpour in an exclusive interview that the U.S. operation is "a very serious provocation, politically and militarily" and the country's foreign ministry summoned Max Baucus, the U.S. ambassador to China, to express its "strong discontent" over the patrol.

Cui said it was a clear attempt by Washington to militarize the region.

"It is a very absurd and even hypocritical position to ask others not to militarize the region while one's self is sending military vessels there so frequently," he said.

A U.S. defense official told CNN that the destroyer USS Lassen "conducted a transit" within 12 nautical miles of five reefs claimed by Beijing, including Subi Reef, in the Spratly Islands on Tuesday morning.