The abrupt dismissal of 40 Iranian ambassadors, almost half of those posted, reveals the extent of the power struggle in Tehran. Hard on the heels of his crass call for Israel to be wiped off the map, President Ahmadinejad has now sacked the senior diplomats attempting to defuse the subsequent diplomatic storm, while at the same time naming an unqualified political hardliner to the key post of oil minister. There could be no better sign that this inexperienced zealot, already running into strong domestic opposition, is lurching into Maoist populism in an attempt to distract attention from the consequences of his own adventurism.

The dismissal of the envoys to London, Paris, Berlin and beyond, including several who have been only a year in post, removes any veneer of moderation from Iran’s foreign policy. It sabotages the slim hope that agreement could be reached with Tehran over its attempt to develop nuclear weapons. It underlines the President’s bellicose refusal to halt uranium enrichment programme and his contempt for Europe’s diplomatic initiatives. And it significantly raises tensions with the West, the United Nations and even countries such as Russia and China that are alarmed by Iran’s return to revolutionary confrontation.

Mr Ahmadinejad’s move, however, may well be a sign of frustration and desperation. He is clearly floundering in his new job. In only a few months he has alienated not only the clerical establishment and the emerging technocrats eager to attract foreign investment; he has also angered core supporters — the poor, the unemployed and the have-nots — who have yet to see results from his election promises on jobs, education, curbing drugs and rooting out corruption. Populist proposals to spend Iran’s expected oil revenue of $35 billion on such schemes as handing out $1,000 to every newly-wed couple are seen as economic madness by local investors and as gimmickry by those whom they are intended to assist. The stock exchange, though it is far from a perfect market, has fallen 20 per cent since the May election.

Though once seen as the cat’s-paw of the clergy, Mr Ahmadinejad has run into opposition from even the conservative-dominated Parliament and, significantly, from Ayatollah Ali Khamanei, Iran’s supreme spiritual leader. Parliament, having already vetoed the President’s first choice for oil minister, is unlikely to accept the new nominee, whose inexperience ill-suits him to run the ministry on which Iran’s entire economy depends. In a further humiliation, Ayatollah Khamanei has now handed overall supervision of the Government to the aptly named Expediency Council, headed by Ayatollah Ali Rafsanjani, the former President and defeated opponent of Mr Ahmadinejad.

The often unpredictable Tehran is about to become even more volatile. The West, in response, should remain watchful, determined and maintain its unity, especially on the nuclear issue. It has plenty of economic weapons in its hand. Even the clerical establishment understands that permanent revolution and pariah status will bring Iran neither prosperity nor respect.