After a bruising Asean meeting that only deepened divisions over the South China Sea, there was barely disguised mirth among some Filipino and Vietnamese envoys last Friday over news that a Chinese naval frigate had run aground on a disputed shoal near the Philippine island of Palawan. Understandable, perhaps, given the roiling tensions between both countries and China in recent months, but the grounding of the Jianghu-class frigate Dongguan - which was successfully refloated on Sunday and is now heading north - is no laughing matter. If anything, it underscores the growing risk of accidents and miscalculation across the South China Sea. Increasing numbers of naval vessels, coastguard ships, surveillance craft and fishing boats now ply troubled waters, their captains and crews ever more conscious of disputed sovereignty - and, in many cases, of the need to keep their flags flying. For several years now, the risk of a deadly miscalculation, or an accident that, fuelled by nationalism, degenerates into something more extreme, has been exercising strategic minds across the region, without a solution. We are left to hope that common sense, aided by good communication, prevails - and any spark is quickly contained. In this case, neither China nor the Philippines have seized the moment to attempt to turn the incident into something more dramatic. Beijing, not surprisingly, has avoided the megaphone diplomacy of recent weeks while the Philippines has avoided lodging a formal diplomatic protest. Its prominent offers of rescue assistance, backed by surveillance flights, were apparently enough of a show of sovereignty for Manila's ends. That does not lessen the significance of the incident, however. It is a reminder that naval vessels still ply sensitive waters, however much publicity is given to the vaunted proliferation of coastguard and other paramilitary vessels - much less provocative than naval ships. Half Moon Shoal sits at the edge of the Spratly archipelago, known as the Nansha Islands in Chinese, and is 60 nautical miles west of Palawan. That means that while it sits well within the Philippines' 200-nautical-mile exclusive economic zone, it is also within China's historical claim, expressed by its controversial nine-dotted line encompassing much of the South China Sea. It is not a heavily militarised area. We are left to wonder, then, whether matters would have been so quickly and quietly dealt with if the frigate had run aground 125 nautical miles or so to the northeast, where the reefs of Tizard Bank are dotted with Vietnamese and Chinese military bases, as well as Taiwan's sole but extensive holding on Taiping Island. Malaysia and the Philippines also have bases elsewhere in the Spratlys. Nowhere in the region, in fact, is such a diversity of militaries so proximate as across the South China Sea. With half the world's shipping tonnage passing through its shipping lanes annually, oil and gas reserves, and a mounting strategic rivalry between China and the US, the growing threat of miscalculation in the South China Sea is something that must be understood - and addressed. Greg Torode is the Post's chief Asia correspondent