Western diplomats have been afraid of this predicament ever since the poll results began to come in, with an apparent lead for President Karzai accompanied by a torrent of allegations of fraud. Mr Karzai is now within a whisker of the 50 per cent that would allow him to him claim victory and prevent a run-off vote. But the huge number of serious allegations of fraud — in the thousands, but with at least 600 material to the outcome of the election — mean that it is hard to take his victory as legitimate.

That, certainly, is the view of Abdullah Abdullah, his main rival, and Abdullah supporters. They are threatening to challenge the result through legal appeals and through violence if necessary. The studied position of British and US officials for the past week —...