Attaching blame is difficult. But at a time of a growing perception in the West that China is flexing its muscles (see article), countries closer to China’s shores also worry that it might be getting more assertive. Their squabbles are often aggravated by rivalry over undersea oil and gas.

Less than two years ago, Japan and China reached an accord on their rival claims in the East China Sea that made it seem as if a long-running war of words might at last be at an end. Now the two countries are at it again. Japan’s press reported that the foreign minister, Katsuya Okada, on January 17th warned his visiting Chinese counterpart, Yang Jiechi, that Japan might take “measures” should China go ahead unilaterally with development of the Chunxiao gasfield (Shirakaba in Japanese).

Chunxiao lies just to the Chinese side of what Japan claims as the line, halfway between the two countries, dividing their exclusive economic zones in the East China Sea. Japan’s fear is that gas extraction in Chunxiao could siphon off gas from Japan’s side of the field. The agreement reached in June 2008 was supposed to allow joint exploitation of the field. But last year Japan noticed activity suggesting that China was moving in drilling equipment and preparing to go ahead on its own. China said it was just conducting maintenance. Japan had expected a detailed agreement on how it might take part to be reached soon after the 2008 accord. China has stonewalled. Only after heated debate did Mr Yang tell Mr Okada that he still “cherished” the pact.

On January 19th the Chinese foreign ministry, in language that recalled frostier times in bilateral relations, said a “proper” handling of the dispute was crucial to relations between China and Japan as well as to regional stability. For good measure, it also weighed in on a more arcane dispute about a tiny Japanese atoll in the Pacific, Okinotorishima. China suspects Japan of trying to build up what China dismisses as “merely a rock” into a proper island. This could reinforce Japanese claims to an exclusive economic zone stretching 200 nautical miles (370km) from the atoll, which happens to lie on a militarily important route between the American island of Guam and Taiwan. Such claims would gravely damage the interests of the international community, said a Chinese spokesman. (And perhaps, he omitted to say, complicate China’s naval activities.)

China is doing some beefing up of its own in the Paracels, an archipelago in the South China Sea also claimed by Vietnam (and, half-heartedly, by Taiwan). In December, to Vietnam’s outrage, China included the Paracels in its plans for promoting tourism in its island-province of Hainan. The Paracels boast fine beaches, but are wholly peopled by that uninviting body, the People’s Liberation Army.

Worries in the region about China’s ambitions have grown since tense encounters in the South China Sea early last year between Chinese vessels and American surveillance ships. In testimony to Congress on January 13th the American armed forces’ Pacific commander, Admiral Robert Willard, said the Chinese navy had increased its patrols in the South China Sea and had “shown an increased willingness to confront regional nations on the high seas and within the contested island chains.” China bristles at any suggestion that it can be a prickly neighbour.

Jan 21st 2010 | BEIJING From The Economist print edition