To an anxiously watching world, the escalation of tensions over Iran?s nuclear programme is evidence of the irrationality of fundamentalist president Mahmoud Ahmadi-Nejad.

But viewed from inside Iran the government?s aggressive approach is based on an entirely rational calculation: that a potent combination of high oil prices, a distracted and overstretched US and Tehran?s potential to foment unrest among allies in the Middle East will ensure the Islamic Republic emerges triumphant from its long months of brinkmanship with the west. In other words, while Iran?s strategy may be dangerous, it cannot fairly be characterised as mad.