HAVING MADE a “rebalancing” toward Asia a pillar of his foreign policy, President Obama may face a fateful test from China in his final months in office. President Xi Jinping already broke a promise he made to Mr. Obama not to militarize islets his regime has been building up in two parts of the South China Sea. Now Beijing appears to be contemplating building a base on a contested shoal just 150 miles from Subic Bay in the Philippines. A failure by the administration to prevent this audacious step could unravel much of what it has done to bolster U.S. influence in the region.

Chinese development of Scarborough Shoal, a collection of rocks and coral reefs it seized from the Philippines four years ago, would escalate its already-belligerent behavior in the South China Sea in a number of ways. Until now, Beijing’s landfill work and construction of airstrips have occurred on islets it already controlled that are considerably closer to the Chinese mainland. Scarborough Shoal lies about 500 miles from China. A base there could allow Chinese radar and missiles to threaten Manila, as well as Philippine bases where U.S. forces are positioned.

Perhaps most importantly, the Chinese venture would concretize Beijing’s refusal to abide by international law in resolving territorial disputes with its neighbors. The Philippines responded to the seizure of Scarborough Shoal by filing a case with a U.N. tribunal. A ruling by the panel, expected in the coming weeks, could reject China’s expansive claim to 80 percent of the South China Sea, based on a “nine-dash line” dating to the 1940s. Acts that defy that ruling, in turn, would suggest that Mr. Xi intends to use brute force to advance China’s claims across the region.

https://www.washingtonpost.com/opinions/dangerous-rocks-in-the-south-china-sea/2016/05/08/e961f34e-115b-11e6-93ae-50921721165d_story.html