U.S. monitoring Chinese activity near disputed South China Sea shoal

U.S. intelligence agencies are monitoring recent Chinese maritime operations near Scarborough Shoal, an uninhabited atoll roughly 140 miles west of the Philippine island of Luzon, U.S. officials said. The officials said China installed a structure described as scientific in the middle of the reef.

Philippine authorities disclosed a 6-by-6-meter floating platform equipped with what appeared to be an antenna inside the shoal earlier this week.

Structure details and responses The Philippine government's National Task Force for the West Philippine Sea said aerial surveillance identified the platform and personnel standing atop it. The task force stated that the Department of Foreign Affairs has undertaken diplomatic action with China regarding the structure.

China rejected the objections. Liu Pengyu, an embassy spokesperson for China, told CBS News that Huangyan Dao has always been China's territory and that activities including scientific research are within China's sovereign rights. U.S. officials said the People's Liberation Army claimed the structure was not military but did not fully disavow that some element could be used by the PLA.

The Office of the Director of National Intelligence has not responded to a request for comment. Scarborough Shoal sits within Manila's exclusive economic zone. Beijing has maintained a near-constant presence around the shoal since a 2012 standoff.