China claims nearly all of the waters, putting it in conflict with a number of regional neighbours, including the Philippines and Vietnam, who argue that parts belong to them.
Last July, an international tribunal in The Hague rejected China’s historical claims over the waters in a case filed by the Philippines. China refused to take part in the proceedings or recognise the jurisdiction of the tribunal.
But tensions between Beijing and Manila have eased in recent months, with Philippine President Rodrigo Duterte paying a state visit to China in October.
Late last month, Philippine Foreign Minister Perfecto Yasay said Chinese President Xi Jinping had pledged China would not build on the Scarborough Shoal, about 250km west of the Philippines’ main island of Luzon.
The United States remains concerned about China’s construction of artificial islands housing military facilities, and expressed fears they could be used to restrict vessel movement in the vital trade route.
Other claimants also have military assets in the area. Vietnam fortified several of its islands last August with mobile rocket launchers capable of striking China’s installations.
