With a successful Group of 20 summit under its belt and the run-up to November's presidential election occupying Washington, Beijing appears to be testing the waters for a potential move on a hotly disputed site in the South China Sea that would further extend its grip there — and significantly ratchet up tensions in the region.

China has in recent days and weeks ramped up its activity around the Scarborough Shoal, with Philippines' Defense Ministry releasing pictures Wednesday showing what it said were Chinese boats near the chain of rocks and reefs just 230 km (140 miles) from the Philippine coast. The release came just hours before Southeast Asian nations were due to meet China's premier at a summit of Southeast Asian leaders in Laos.

The moves have stoked fears in Manila that Beijing could be laying the groundwork for an eventual land-reclamation project at the contentious collection of rocky outcroppings that barely jut above water at high tide.