It is quite possible that Mahmoud Ahmadinejad first learnt about sabre-rattling at his father’s blacksmith’s shop in Tehran. The Persian sabre, or shamshir, has a sharply curved narrow blade that requires an exact fit inside its scabbard, and to an apprentice’s ear any undue clank or jangle would suggest a botched job.

Many people now wish that Iran’s president had stuck to his father’s profession, or at least pursued his PhD in traffic management. Instead, the combative leader is giving everyone the heebie-jeebies as he fires off volleys of missiles in a game of brinkmanship that could, it is feared, lead to war between America and Iran.

Once again the world’s gaze is fixed in alarm on Ahmadinejad, a tiny, wiry figure with a gaunt face and eyes that do not change expression as he spouts combustive rhetoric. This devotee of football and technology, devout husband of a university lecturer and father of three children, has spoken of being bathed in a green light from heaven. He says that he yearns for a Shi’ite saviour, the 12th imam, to return and bring about the final apocalypse.

One school of thought holds that Iran’s second launch of powerful Shahab-3 rockets across the Gulf in the space of a week was Ahmadinejad throwing the toys out of his pram in fury at America’s studied indifference to his provocations. Since coming to power in 2005, the 51-year-old president has gone out of his way to outrage the West, declaring that Israel should be wiped from the map, that the Holocaust is a myth and that Iran has an inalienable right to nuclear power – potential cover for nuclear weapons.

Lately he has called for US military bases across the world to be “eradicated” and promised to strike at Tel Aviv if Iran were attacked. He has also threatened to close the Strait of Hormuz, the conduit for 40% of the world’s oil supplies, in retaliation.

According to this theory, the show of force was Ahmadinejad’s attempt to divert attention from his failures on the domestic front. If so, it did not go to plan. The official photographs showing the launch of four Iranian missiles on Wednesday were faked. One commentator joked that sophisticated western technology had fallen into Iran’s hands – “Good news: it’s Photoshop.”

However, some Tehran watchers doubt that Ahmadinejad’s finger was anywhere near the firing button or that he was staging a distraction. As president, they point out, he has no authority over the armed forces.

“There’s a much simpler explanation,” said Richard Dalton, a fellow of the Royal Institute of International Affairs. “When you get threatened explicitly and repeatedly, you want to show you have the capability of hitting back.” In his opinion, the rocket display was a predictable reaction to Israel’s aerial manoeuvres in the Mediterranean a month ago, which resembled a trial run for a bombing raid on Iranian nuclear facilities.

Karim Sadjapour, an analyst at the Carnegie Endowment, a Washington think tank, believes that the exercise was ordered not by Iran’s firebrand president but by Ayatollah Khamenei, the country’s supposedly more moderate “supreme leader”.

However, few experts dispute that Ahmadinejad’s policies have left Iran’s economy in disarray. With inflation running at an estimated 14% and one-third of the population unemployed, his goal of “putting the petroleum income on people’s tables” is as distant as ever. At one point in 2006, vegetable prices tripled and housing prices doubled within a matter of months, prompting calls for him to focus on the economy rather than on disputes with the West.

After a purge of academics, students disrupted his speech at a Tehran polytechnic, setting fire to photographs of him and throwing firecrackers. A student website accused him of corruption, mismanagement and discrimination. Middle-class women resent his strict dress code. Human Rights Watch has reported “routine torture” under his regime.

His pugnacious foreign relations, which have resulted in oil production running far below its potential, are seen as a dangerous folly by many middle-class Iranians. Last year a Tehran website poll of 20,000 people found that 62.5% of those who voted for him in 2005 would not do so in next year’s presidential election. But the result is difficult to predict, as Ahmadinejad has assiduously courted his natural constituency in rural areas, pushing through small business loans and stalled projects.

The recurrent question is why Khamenei does not rein him in, beyond criticising his “personalisation” of the nuclear issue. One answer is that whatever the supreme leader’s reservations, he does not dictate the government’s day-to-day policies. However, Ahmadinejad’s powers are more circumscribed than most prime ministers, requiring him to defer to his colleagues. “Ahmedinejad’s influence on the nuclear file has waned,” said Sadjapour.

Ahmadinejad was born in the shadow of the Alborz mountains on October 28, 1956, the fourth of seven children. He was one year old when his father, Ahmad, decided to improve the family’s lot by moving to Tehran to work as a blacksmith. In his official blog, the president recalls that his father was “a hard-bitten toiler blacksmith, a pious man who regularly participated in religious programmes”.

The boy showed an early interest in reading the Koran. “He liked to go to classes but they threw him out because he was too young,” said his cousin, Maasoumeh Saborjhian. “But he would insist, saying, ‘No, no, I know how to read the Koran’.”

At high school he rankled at “the crapulence of [the Shah of Iran’s] debauched clan and their foreign companies”. An intelligent youth (“I was a distinguished student”), he ranked 130th in the nationwide university entrance exams in 1975 (“although I had nose bleeding during the test”) and was admitted to the Iran University of Science and Technology (IUST) to study civil engineering. He was a committed political activist, printing leaflets at home denouncing the “traitorous” shah. At one point his activities forced the family into hiding to avoid arrest by the Savak, the shah’s secret police.

In 1979, the year of the shah’s overthrow, he was the university’s head representative to the student gatherings that occasionally met his “valiant” hero Ayatollah Khomeini, the country’s new ruler, and he became a founder member of the Office for Strengthening Unity, the student organisation linked to the seizure of the US embassy. On receiving his doctorate in traffic management and engineering in 1987, he became a civil engineer and a professor at IUST. However, he had also joined the Revolutionary Guards and saw action during the Iran-Iraq war. Then his remarkable ascent began. After the war, he served as vice-governor and governor of the provinces of Maku and Khoy and then governor of Ardabil from 1993 to 1997.

Questions have emerged about Ahmadinejad’s murky past. Former hostages taken captive at the US embassy in Tehran in 1979 and held for 444 days have claimed that he was one of the ringleaders. Don Sharer, a retired navy captain, remembered him as “a cruel individual”. There are also claims that Ahmadinejad played a part in the assassinations of political opponents, notably Abdul Rahman Ghasse-mou, the exiled Kurdish leader, and two of his associates in Vienna in 1989.

Ahmadinejad was almost unknown when he was elected mayor of Tehran in 2003 on a 12% turnout. He reversed many reforms and put more emphasis on religion while courting popularity by distributing soup to the poor.

During the presidential campaign in 2005, he contrasted his spartan imag with the lavish lifestyle of Ali Akbar Hashemi Rafsanjani, the now 74-year-old former president. He had few campaign funds, but his focus on ordinary people and the fact that he was not a mullah made him seem like a breath of fresh air.

Why does he love goading the West? “He’s an engineer and sees things in black and white,” said one analyst. “It’s partly his rough manner, but it’s also a philosophy that Iran, with its history, religion and resources, should turn its back on the outside world.”

Last month Ahmadinejad seemed to relish the prospect that if Iran’s enemies “close all the doors in front of Iran” the nation would be free to develop by itself. At this rate, that day may arrive sooner than he thinks.

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