In a move likely to stoke tensions in the region, China has built new structures to potentially house surface-to-air missiles on three of its artificial islands in the South China Sea, but so far no missiles have been sent there, two U.S. officials confirmed to Fox News.

The news comes as the U.S. Navy deployed an aircraft carrier to the South China Sea during the weekend -- the first time since President Trump took office.

China has built runways on Subi, Mischief and Fiery Cross islands, built atop former reefs in the Spratly chain of islands. China has constructed 24 new buildings across these three islands in the past few months, according to the officials.


Recent U.S. satellite imagery showed that each structure is 11-by-22 yards in length, according to one official. The buildings have retractable roofs.

Surface-to-air missile systems don’t need to be covered or housed, but the new buildings likely will help conceal the missiles should they arrive and also protect them from the salt air, one official said.

Fox News exclusively reported on Dec. 24 that China had amassed hundreds of surface-to-air missiles on Hainan island just off the mainland for training, and intelligence officials believe they could be sent to China’s man-made islands next. So far, though, none of the missiles have been shipped south to the artificial islands, according to officials.

U.S. officials said they are also seeing signs that Russia is preparing to deliver advanced SA-21 launchers to China, which could one day end up on the artificial islands.

Secretary of State Rex Tillerson, in his confirmation hearing in January, told lawmakers China should be denied access to its artificial islands in the South China Sea.

Over the weekend, the aircraft carrier USS Carl Vinson and her strike group patrolled in the South China Sea, conducting what the Navy called “routine operations.” A few hours ago, the U.S. Pacific Command tweeted photos showing a U.S. Air Force B-1 bomber flying in formation with F/A-18 Hornets over Vinson in the South China Sea.

On Tuesday, a Chinese military spokesman said he opposed the presence of the American aircraft carrier in the region.

"We are consistently opposed to relevant countries threatening and damaging the sovereignty and security of littoral countries under the flag of freedom of navigation and overflight," Chinese foreign ministry spokesman Geng Shuang said at a news briefing according to Reuters, the first official comment since the aircraft carrier strike group began its patrol in the South China Sea.

Reuters first reported the presence of new buildings on the man-made islands in the South China Sea.