China may be preparing to mobilise "hundreds" of its surface-to-air missiles currently stationed in Hainan Island.
US military officials said the missiles, which Beijing recently shipped to its non-contested Hainan Island in the South China Sea, will be moved to the country's disputed man-made islands over coming months.
The officials told Fox News Hainan Island would likely serve as a training site before the missiles are deployed early next year to the disputed Spratly Islands or Woody Islands.
The equipment includes a number of short, medium and long-range weapons. One of these, a military unit of the advanced SA-21 system, would be capable of knocking out aircraft from more than 400km away.
The officials also said the total number of surface-to-air missiles on Hainan could reach 500.