U.S. monitoring Chinese activity in South China Sea around disputed shoal

China placed a floating platform with an antenna at disputed Scarborough Shoal, prompting protests from the Philippines.
U.S. intelligence and military planners are closely monitoring the site, worried it could be a step toward a more permanent or militarized presence.
Beijing says the installation is for research and defends its sovereignty, but the move fuels ongoing regional tensions after years of Chinese island-building.