China and US join calls for restraint amid fears of regional meltdown

Both China and the US are urging calm in the new flare-up between the two Koreas, underlining the concern of both powers that the exchange of shelling does not lead to wider hostilities at what appears to be a moment of particular instability within the closed Pyongyang regime.

The Chinese Foreign Ministry expressed the hope that "the relevant parties will do more to contribute to peace and stability in the region", adding that it was "imperative" to restart the stalled six-country negotiations on ending Pyongyang's nuclear programme.

In fact, that is now less likely than ever, not only because of the North's shelling of the South Korean island, but because of the latest evidence of an advanced uranium enrichment facility in the North.

The reaction in Washington to one of the most serious incidents since the end of the 1950-53 Korean War was also measured. President Barack Obama was due to discuss the crisis with South Korea's President Lee Myung-bak. But although the US condemned the attack, the Pentagon gave no indication of any further immediate response.

Nor are more sanctions likely. "It's hard to pile more sanctions upon the North than are already there," a Pentagon spokesman said, noting Pyongyang's long record of unpredictability. "They do things that you could not possibly have predicted in a rational world."

Neither China nor the US has any interest in seeing this latest Korean confrontation spin out of control. Whatever its traditional ties with the regime in Pyongyang, China will seek to avoid antagonising the US, despite the recent frictions between them on trade and currency issues.

North Korea's leader Kim Jong-il has already visited Beijing twice this year to strengthen ties and the isolated North now relies on Chinese economic aid more than ever, given the deterioration in relations with South Korea, further strained by the North's sinking of a South Korean warship in March.

For China's part, the last thing it wants is a collapse of the North Korean regime that would produce a tide of refugees, and almost certainly lead to a re-unified Korea on its north-eastern border, aligned with the West and with 28,000 US troops as well as US nuclear weapons on its soil.

According to Jin Canrong, deputy dean of the Academy of International Relations of Renmin University, North Korea is seeking to force Washington into negotiations. "South Korea will be really angry," he said, "but the South Korea-US side does not have the capacity to punish North Korea".