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.
Seeing such statements, one Southeast Asian diplomat said China may have picked the perfect fight to drive a wedge into diplomatic efforts to shape and respond to China's rise. However, it risks further highlighting Chinese assertiveness in the South China Sea.
'We're all watching to see who is going to blink first,' said Professor Carl Thayer of the Australian Defence Force Academy, a scholar who has studied South China Sea issues for four decades.
'My money is on China [not to blink]. They are ever more prepared to ride this one out. It is all so strategically wrong for the Philippines. As this drags on, the very effort of keeping ships out at Scarborough will be like a major overseas deployment for them. Their officials keep on vowing to defend their territory, but they clearly don't have the ability to. It is damaging to their credibility.'
Professor Jean-Pierre Cabestan, head of the department of government and international studies at Hong Kong Baptist University, said the stand-off had the potential to expose the limits of the US alliance with the Philippines. While the US may work to boost the Philippines' coastguard and armed forces in coming years, its treaty was ambiguous when it came to defending the Philippines over its South China Sea claims. And Washington would be reluctant to be drawn militarily into a bilateral territorial dispute involving China - even as it has deepened its involvement in the South China Sea issue, he said.
The latest stand-off began on April 8, when officers from a Philippine warship boarded and searched Chinese fishing boats found near the shoal in what Manila insists is a breach of Philippine law. Scarborough - known as Huangyan in Chinese - sits within the Philippines' 200-nautical-mile exclusive economic zone claimed under the UN Law of the Sea, an agreement signed by China. But it also sits within China's controversial nine-dotted line encompassing almost the entire South China Sea and is the subject of an historic claim by Beijing.
Chinese civilian vessels moved in to protect the fishing boats, and, as diplomatic manoeuvring intensified, the Philippines replaced the warship - its largest and a vessel recently obtained from the US Coast Guard - with its own coastguard ships.
The Chinese fishing boats left under Chinese protection but Beijing later reinforced its presence of China Marine Surveillance and Fisheries Law Enforcement Command vessels, as well as more fishing boats. This week has seen two vessels from each agency backed by support ships including a 20,000-tonne oil tanker and a 32,000-tonne fish-processing ship. The Philippines is keeping coastguard and small paramilitary vessels in the area.
Amid nationalist tensions in both countries, both capitals have vowed to find diplomatic solutions - even as their own diplomatic rhetoric escalates. Foreign Ministry officials have warned Manila that it is ready for 'any escalation' and accused Manila of 'provoking public feelings' in China - a charge denied in Manila.
Thayer said that while there was a sense of dej?vu to the current stand-off - Scarborough has been the centre of several flare-ups between China and the Philippines in recent years - it plays into an increasingly complex regional situation.
Those earlier events suggest little hope for a short-term solution.
In April 1997, for example, the Philippine navy intercepted two ships from the State Oceanic Administration that were carrying amateur radio enthusiasts to the shoal to make a broadcast from the reef. The Chinese ships called their Philippine counterparts and formally declared China's sovereignty, before eventually withdrawing.
A month later, a group of Philippine congressmen removed a Chinese flag that had been placed on a boundary marker, replacing it with a Philippine one and drawing Chinese diplomatic protests. Recent mainland press reports noted that a Chinese flag was placed back on the marker late last month.
The mid-to-late 1990s sparked a flood of interest in China's long-term ambitions in the South China Sea, with Beijing occupying and building structures on Mischief Reef - also claimed by Manila and within its economic zone. Despite regional criticism at the time, those structures remain, with Philippine officials vowing privately never to be caught off guard again.
The years from 1999 to 2002 saw a host of incidents over Scarborough - many couched in the same diplomatic rhetoric heard this time around, with China formally warning against provocations and Manila of 'hostile acts' and the illegality of Chinese fishing activity.
In May 1999, the crew of a wrecked Philippine naval ship complained that rather than rescue them, a passing Chinese patrol trained its guns on them but offered no assistance. Then, a few days later, both sides argued over the sinking of a Chinese fishing boat after a collision with a Philippine naval ship. Three crew were rescued and returned to China.
In February 2001, China lodged diplomatic protests over the armed boarding of four fishing boats at Scarborough, with the Philippine side saying the Chinese had been fishing for sea turtles - a protected species.
In the drawn-out legal game of territorial disputes, protest and countermove are vital if sovereignty is to be proved in court. While China points to ancient history, Manila points to proximity and evidence of occupation. Even so, Baptist University's Cabestan notes that Manila has 'woken up a bit of late', pointing to its abandonment of a lighthouse on Scarborough in the 1960s.
'They couldn't even be bothered with changing the light bulb,' he said. 'These things all count when you are arguing sovereignty'.
Right now, it's a stalemate. Manila wants Beijing to keep its obligations under the Law of the Sea and go to an international court. Beijing is not budging. And even though Asean is loath to wade into a bilateral issue, Manila is refusing to give in to Beijing's demand for one-to-one talks.
In the background, a nervous region can only watch and wait.
The highest point on islands and reefs making up Scarborough Shoal. Many of the reefs are just below water at high tide
Staking their claims in the South China Sea
Claims almost all of the South China Sea, including all of the Spratly Islands. Seized the Paracels from Vietnam in 1974. China's claims are based on historical records of the Han (AD110) and Ming (1403-1433) dynasties
Occupies eight of the Spratly Islands. Claims are based on its 200-nautical-mile exclusive economic zone (EEZ) under UN law, as well as on the 1964 continental shelf treaty and a 1956 Filipino explorer's expedition