North Korea has, at the best of times, to be treated with kid gloves. The unpredictability of its leadership, bristling armoury, war-ready military and secrecy make for a volatile mix. With its hand increasingly being seen in an explosion that sank a South Korean navy vessel last month, killing 46 sailors, pressure is mounting on the South's president, Lee Myung-bak, for a resolute response. He is being cautious, and rightly so: circumstances have to be handled with extreme care.
There is as yet no certainty of North Korea's guilt. It has denied involvement and investigators have found no evidence. But examination of the wreckage of the 1,250-tonne Cheonan indicates the blast was external, pointing to a torpedo or floating mine as the most likely cause. On Sunday Defence Minister Kim Tae-young stepped where no other South Korean official has so far dared. As his nation started five days of mourning he said there was a high possibility that a torpedo was to blame.
Anger is rising in South Korea. Tens of thousands of people have visited a memorial honouring the dead, who have been posthumously awarded medals usually reserved for those killed in combat. The media is awash with speculation and calls for retaliation. There's a real danger of the situation spinning out of control.
The Cheonan was on a routine patrol on March 26 when it was split in half in an area where the rival Koreas have had three naval skirmishes since 1999. In the last, five months ago, a soldier from the North was killed and three others wounded. Given the North's history of provocation and attack, assuming a missile had been fired to avenge the loss would not be far-fetched. But for South Korea or its allies to make this leap without conclusive proof could have disastrous consequences.
Six-party talks led by North Korea's closest ally, China, to get it to scrap its nuclear programme have faltered. In the absence of negotiations and amid speculation that the North's leader, Kim Jong-il, is in poor health and preparing to hand power to one of his sons, instability troubles the Korean peninsula. It continues testing its missiles, which can easily reach all parts of the South. A misplaced accusation could easily lead to a new Korean war, ending the truce that has held - albeit flimsily at times - for the past 57 years.
How Lee should respond is a difficult matter. He can't remain silent or evasive much longer given the domestic pressure. Even if there is proof of the North's involvement, he and his main foreign ally, the US, have to remain cool-headed. Military force is not an option; both sides and their alliances are militarily evenly balanced.
Fortunately, China and the US have already been in contact with one another. Neither, surely, has an appetite to be dragged into a conflict that they would be obliged to join should it break out. The North's unpredictability means that even calling for tougher UN sanctions or curtailment or an end to South Korean aid and business partnerships could have dire consequences. Behind-the-scenes intervention by Beijing and Washington is crucial to calming what could quickly turn into a crisis for Koreans and the region.
A delicate situation has arisen. If North Korea is found to have attacked the ship, it has to be punished; no nation can wantonly kill foreign citizens, no matter what the circumstances. But Lee has no good options. Whichever he chooses has to be picked with great forethought and enacted and managed just as sensitively.