US Navy Destroyer Sails Near Disputed Chinese Islands

A US defense official told CNN that the destroyer USS Lassen "conducted a transit" within 12 nautical miles of Subi Reef in the Spratly Islands on Tuesday morning local time.

The operation put the ship within an area that would be considered Chinese sovereign territory if the US recognized the manmade islands as being Chinese territory, the official added, according to CNN.

The mission, which had the approval of President Barack Obama, has now concluded, the official said.

The United States had not breached the 12-mile limit since China began massive operations to turn three reefs into artificial islands in 2014.

In little more than 18 months, China has reclaimed more than 2000 acres at three main locations in the Spratly Islands -- Subi, Mischief and Fiery Cross reefs.

The South China Sea is the subject of numerous rival and often messy territorial claims, with China, Brunei, Malaysia, the Philippines, Taiwan and Vietnam disputing sovereignty of several island chains and nearby waters.

On Tuesday morning before it was confirmed that the US warship had breached the 12-mile zone, Wang Yi, China's foreign minister, said:

"We advise the US side to think twice before action, not to conduct any rash action, and not to create trouble out of nothing."

China has repeatedly said its activity in the South China Sea does not target any other country or affect freedom of navigation by sea or air.

In May, a US surveillance plane carrying a CNN crew swooped over the Spratly Islands, triggering eight warnings from the Chinese navy to back off.

'Routine operation'

Another defense official claimed in an interview with CNN that the operation was "routine" and was in accordance with international law.

"We will fly, sail and operate anywhere in the world that international law allows," the official said.