The South China Sea: Shoal mates PHILIPPINE and American troops charged ashore from the South China Sea on April 25th in an exercise to show they could jointly recapture a small Philippine island from hostile forces. It was all make-believe, of course: just another round of a game in which China pretends it owns almost all the South China Sea, and the Philippines and four other East Asian countries pretend otherwise. America says it does not take sides in the squabble embroiling China, Taiwan, Vietnam, Brunei, Malaysia and the Philippines over ownership of all or parts of the South China Sea. The sea has (or had) a rich marine life, and oil and gas. But America does play chicken. It has a mutual-defence treaty with the Philippines, which an American general this month described as "self-explanatory." However, the treaty fails to spell out whether America would help defend Philippine-claimed territory if it was also claimed by China. In this way, America keeps China guessing as to where the tripwire for armed conflict is buried. The Americans and Filipinos made the usual denials that the mock enemy in their annual joint military exercises is China. The Chinese muttered darkly that the exercises would increase the risk of confrontation. Its press was even more incensed, since joint exercises with Vietnam, another rival claimant to parts of the sea, also began on April 23rd. America insisted this was coincidental and that the exercises had long been planned. Tensions were high because a real mix-up between China and the Philippines was already taking place - over Scarborough shoal, a ring of mostly submerged rocks that both claim. On April 10th a Philippine warship found Chinese fishing boats inside the shoal with an illegal haul of giant clams, coral and live sharks. The fishermen called for help, and two Chinese civilian patrol boats blocked the mouth of the shoal to stop the Philippine navy from arresting the fishermen. The Filipinos were not playing the South China Sea game as the Chinese expect it to be played. A new report by the International Crisis Group (ICG), a think-tank, says that China, while asserting its vague claims to territory in the South China Sea, is actually averse to confronting other claimants, particularly in view of America's strengthening of military ties with some of China's neighbours. But the ICG argues that various agencies of the Chinese state are exploiting its claims for their own interests, whether it is the navy seeking to justify funds for its modernisation, or local governments encouraging fishermen to go farther afield in search of bigger catches. This causes trouble with other claimants. The foreign ministry tries to ease tension, but often lacks the clout. And the vagueness of China's claims in the South China Sea means that other agencies can interpret them more liberally than the foreign ministry would. The Scarborough shoal confrontation unfolded just as the ICG's argument would suggest. The Chinese foreign ministry had to defend poachers in what it had to argue was a traditional Chinese fishing ground. It persuaded the Philippines to withdraw its warship and replace it with a civilian coastguard vessel, perhaps with a view to keeping the Chinese navy on the sidelines. China then withdrew all but one of its civilian patrol boats. The Philippines hoped that both sides could then pull back from the shoal, ending the confrontation. But Chinese patrol boats from at least two government agencies kept returning, perhaps in defiance of foreign-ministry advice, and eventually so did some Chinese fishing vessels. The ambiguity of China's behaviour may be like the ambiguity of America's defence treaty with the Philippines: it keeps antagonists guessing. But chicken can be a dangerous game.