China has built new military facilities on the contested Spratly Islands in the South China Sea, a U.S. think tank said Thursday. The Asia Maritime Transparency Initiative said missile shelters and radar and communication facilities are visible in new satellite images of the Fiery Cross, Mischief, and Subi Reefs in the Spratlys. “Beijing can now deploy military assets, including combat aircraft and mobile missile launchers, to the Spratly Islands at any time,” AMTI said. Beijing reportedly built four new missile shelters on Fiery Cross Reef, while a large antenna array that will boost monitoring capabilities is under construction on Mischief Reef. The U.S. has warned China against militarizing the area or restricting free movement through the sea, drilling the message home last month when the U.S. Navy conducted its first freedom-of-navigation operation under President Trump.