A little over a year ago, the world's big powers set Iran an ultimatum - to stop those parts of its nuclear programme that could help it build the bomb. But the Islamic Republic has brazenly refused to comply with the United Nations Security Council's demands.

That leaves the international community three options in the run-up to the first anniversary of the original deadline of August 31 2006. The outside world must choose whether to do nothing, to strike Iran militarily, or to increase sanctions on Tehran while holding out the prospect of negotiations. Since the first two options could both be disastrous, the last one - of using both carrot and stick to coax Tehran away from its nuclear ambitions - is clearly the best.