China has built military weapons on some contested islands in the South China Sea, according to a U.S. think tank.
The Asia Maritime Transparency Initiative tracks changes on three island chains using satellite images. The group says recent images show China constructed anti-aircraft guns and other weapons systems on seven artificial islands it created in the Spratly Island chain.
AMTI said, "Among other things, they would be the last line of defense against cruise missiles launched by the United States or others against these soon-to-be-operational air bases."
The Spratly Islands consist of more than 100 small islands and reefs in the South China Sea. Taiwan, Vietnam, Malaysia and the Philippines have all claimed some of those islands, but the Chinese government says it owns the majority of the region.
If a conflict erupted in the South China Sea, it could affect the global economy. The Council on Foreign Relations estimates $5.3 trillion of trade passes through the area and that over $1 trillion of those goods are traded to or from the U.S.
The Chinese government denies claims that the construction is for military use.