For Mahmoud Ahmadinejad, the Israeli attacks on Gaza could not have come at a better time. Beset by rising unemployment, stagnating living standards and anger among the urban poor at his failure to deliver promised improvements, the Iranian President's chances of re-election in June looked bleak. Now he can again rail at Islam's enemies, call for suicide bombing volunteers, mobilise support for Hamas and Hezbollah and invoke revolutionary clichés to reassert his power at home and Iran's radical leadership overseas.

More importantly, he can use the conflict to exacerbate relations with America - stepping up the supply of arms and missiles to Hamas fighters, undermining Western-aligned Arab governments and repeating crude calls for the destruction of Israel. The aim, like that of a spoilt child denied attention, is to provoke and annoy until he is again the focus of America's exasperation. For what Mr Ahmadinejad fears, above all else, is any rapprochement between Iran and Washington. That would strengthen his domestic opponents, embolden a restless younger generation, reopen Iran to Western influence and sideline him, his obscurantist clergy and the thuggish enforcers of social control among the Revolutionary Guard.

Barack Obama's campaign promise to consider talks to end 30 years of hostility is astute. It would deny Iran's Islamist nationalists their strongest card: the invocation of the US threat to justify intrusive clerical vigilance against Western “subversion”. It would make it harder to hold out against pragmatists looking for ways to bring Iran out of its isolation. And it would be seized on by a pro-American generation desperate to escape the suffocating strictures of a killjoy regime.

This, alone, is strong reason why the incoming US president should break the impasse. He needs to do so quickly: before the hardliners in Tehran have honed strategies to thwart him, before opposition asserts itself in America and before the rapid development of nuclear technology puts Iran in a position to build a nuclear weapon.

Mr Obama needs to begin gradually. Any sudden volte-face would be trumpeted by the clerical establishment as a victory. It would be used by Mr Ahmadinejad to widen his appeal to young voters. And it might be used to show that the defiance of world opinion and Western sanctions over Iran's nuclear research is virtually cost-free. There are many steps that Washington could take, however, that would slowly isolate the hardliners while helping to resolve the conflicts on which they base their demagoguery.

First, Washington should return American diplomats to Tehran. None has been based there since the 444-day siege of the embassy ended in 1981, with Washington having to rely on Swiss intermediaries. Second, the US should begin technical discussions, probably in international financial forums, on releasing frozen Iranian assets and easing some of the trade embargoes. Third, Washington should continue and expand low-level talks on guaranteeing stability in Iraq. And fourth, Mr Obama should simultaneously entertain overtures to Syria with the aim of breaking the Iranian axis. There will be no swift breakthrough. But just as Richard Nixon's secret diplomacy paved the way for his coup in China, so Mr Obama now has a chance to end one of the region's longest and most destructive quarrels.