China is likely to deploy the “hundreds” of surface-to-air missiles dispatched to Hainan Island at the man-made islands in the disputed South China Sea, two U.S. military officials told Fox News on Saturday.

The speculation comes after Beijing expressed desire to protect its three airstrips on three of the man-made islands in the contested region. The deployment is expected to begin in early 2017. According to the Fox News report, the two U.S. officials have seen satellite images that showed the missiles were at Hainan Island, which may serve as a training site before the missiles are deployed to the disputed Spratly Islands or Woody Islands. The surface-to-air missiles on Hainan included the CSA-6b and HQ-9.

China had reportedly put up missile systems to Woody Islands in the disputed region earlier this year.

This follows a report earlier this month that said Beijing had build large defense systems on the South China Sea’s disputed Spratly Islands. The Asia Maritime Transparency Initiative, a branch of the Center for Strategic and International Studies that started tracking China’s island buildup over the summer, posted seven photos — dated between Nov. 10 and Nov. 29 — showing several hexagon-shaped structures, evidence of “buried chambers” and platforms “consistent with the pattern of larger anti-aircraft guns.”

China has laid claims to almost all of South China Sea, through which about $5 trillion worth of maritime trade passes every year. It has also reportedly been building runways and ports on islands in the contested waters to assert its claim over the region. Beijing has consistently defended its actions, saying it does not intend to start a conflict and that its operations will add to the safety of the region.