Leading article: Unpredictable and isolated

Kim Jong-il, the only hereditary leader in the Communist world, failed to turn up yesterday at the parade to mark the 60th anniversary of the foundation of his state, North Korea. US intelligence suggested that he is seriously unwell, and may have had a stroke. Reports from Beijing say that five Chinese doctors had been in the Communist state for more than a week, possibly to treat the president. From Japan there was even a claim that North Korea's leader has in fact been dead for five years and has been played in public by four look-alikes trained by Kim in early years to foil assassination attempts.

If that sounds comic, the situation in North Korea is not one which otherwise inspires levity. Last month the country reportedly began to reactivate the nuclear weapons complex it had begun to shutdown as part of an international agreement. Work had begun on taking apart theYongbyon nuclear plant, built during the Soviet era, after a deal struck with five regional powers last November. Pyongyang had agreed to stand down as a nuclear power in return for economic and political inducements from the United States and its allies. This was hailed as a major diplomatic victory for the Bush administration.

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But the deal seems to have foundered in the past few weeks with North Korea angry that Washington has failed to drop it from the US terrorism blacklist and the Americans insisting that Pyongyang must first agree to the independent verification of its nuclear shutdown.

More strident noises have been coming from north of the Korean border in recent weeks. Its Workers' Party, cabinet and army have just issued a statement in praise of Kim for "powerful war deterrent that can safeguard the nation's survival". It is hard to decipher this. Increases in propaganda, and the stoking up of fears about a possible American invasion, are often a sign of internal tensions in the North Korean government.

Whether Kim Jong-il is well, ill or even dead is in one sense irrelevant. North Korea is a nuclear-armed regime led by a group of generals who are as unpredictable as they are isolated. It is vital that the outside world plays its hand with the utmost care.