Leading article: The limits of Chinese influence

The complex politics of north-east Asia continue to tie the leaders of the region up in knots. At a summit in South Korea over the weekend, the Chinese Premier, Wen Jiabao, refused to blame North Korea for the sinking of a South Korean warship, the Cheonan, two months ago on the maritime border between the two divided states. The Chinese Premier also gave no indication over whether his country will use its veto in the United Nations Security Council to block sanctions against the North being sought by Seoul and Washington. The furthest the Chinese Premier would go was to call for all involved to "refuse tensions".

Reading North Korea's intentions is almost impossible. One explanation for its recent bellicose behaviour is that it wants to extort aid from the rest of the world. It has used its nuclear capacity at various times in recent years with this goal in mind. The attack on the Cheonan could be another means to that end. Another explanation is that this all relates to Kim Jong-il's plans to name a successor.

Yet whatever the motivation, it is most unlikely that the Chinese Premier genuinely believes there is reason to doubt the results of the multinational investigation which found North Korea to be responsible for sinking the Cheonan. It is more likely that Beijing believes it is preferable to use its private influence to try to rein in Pyongyang, rather than to allow international sanctions to be imposed which could destabilise the neighbouring Communist regime with potentially harmful consequences for China.

It is true that China, as North Korea's largest trading partner and the provider of the fuel that keeps the Communist regime running, is the only nation with any real leverage over Pyongyang. But there has been precious little evidence of this behind-the-scenes influence from Beijing restraining North Korea in recent years. China's appeals for Pyongyang to scrap its nuclear weapons have yielded nothing. And the North's bellicosity is exacerbating the volatility of global financial markets, something that is hardly in China's economic interest.

Perhaps there will come a day when Beijing comes to the conclusion that the perceived advantages of protecting North Korea are outweighed by the damaging consequences of its neighbour's aggressive behaviour. But the latest signs are that we are still depressingly far from any such moment of enlightenment.