It may be a tiny cluster of rocks barely visible at high tide, but Scarborough Shoal is exposing some of the region's most dramatic fault lines.
A graveyard for shipping for centuries - including the tea ship that sank with all hands in the 18th century to give the reef its name - Scarborough could yet prove a graveyard for regional stability, some analysts fear.
As a stand-off between China and the Philippines over sovereignty of the shoal - 124 nautical miles west of Luzon - enters its second month, analysts and envoys are scratching their heads, wondering when and how it is going to end.
On one side is a rising China, determined to assert sovereignty in the face of what Beijing insists are Philippines' 'provocations' - and armed with an expanding fleet of civilian fisheries and marine patrol vessels designed for this very purpose. On the other side is the Philippines, the weakest regional ally of a US keen to re-engage across East Asia and home to an ageing military operated by leaders long unsure how to live up to promises of defending their territory.
But the stand-off also resonates beyond Beijing and Manila, feeding into wider uncertainties over the extent to which Washington can effectively protect its evolving network of allies and partners on the periphery of an ever-stronger China. And then there is the struggle by members of the Association of Southeast Asian Nations (Asean) to find a way to ease tensions with China over the disputed but oil-rich South China Sea until broader questions of sovereignty can be solved.
As Dr Wang Hanling, a mainland expert on maritime law at the Chinese Academy of Social Sciences, said: 'We have to fight back now.' He noted US support for China's smaller neighbours in their disputes with Beijing and said that China 'was forced to make a strong reaction' amid aggressive moves by neighbouring states in dragging in Washington.