Iranian protesters will try to take to the streets of Tehran this morning in an effort to revive opposition to the government, but those demonstrators who do appear are likely to be chased, beaten or arrested by thousands of riot police and baton-wielding militiamen.
The attempt by the Green movement, as anti-government activists are known, to emulate the protests across the Arab world is failing to shake the Iranian authorities, still less overthrow them. Over the past week the centre of Tehran has been calm with protesters making a negligible impact.
"The regime has got good at calibrating the exact amount of force necessary to frighten people without creating martyrs," lamented a critic of the government. "The Greens showed that they can still mobilise support by their first big protest for over a year on 14 February, but since then fewer and fewer people are taking to the streets."
The government of President Mahmoud Ahmadinejad, whose allegedly fraudulent election in 2009 led to three million people joining protest marches, has been playing its cards carefully. Its officials say they have put the leaders of the Green movement, Mirhossein Mousavi and Mehdi Karroubi, the defeated candidates in the election, under a highly restrictive house arrest. They cannot communicate with the outside world and their families are not allowed to see them. The government insists they are not in jail, a move that might provoke serious demonstrations.
Given that the present system of Islamic government in Iran is the outcome of the street protests of 1978-79 it is hardly surprising that it has always been edgy about anybody else trying to take the same route to power.
Overall the uprisings in the Arab world have greatly strengthened Iran because they have disrupted the political and economic siege that the US has succeeded in imposing on Tehran in recent years. Hostile leaders of Sunni Arab states closely allied to the US such as President Hosni Mubarak, who was always seeing an Iranian or Shia Muslim hand behind every development, have either lost power or are wondering how long they can cling to it. King Abdullah of Saudi Arabia and other Gulf state rulers who, according US diplomatic cables published by WikiLeaks, had been quietly egging on the US to attack Iran, now have troubles closer to home to worry about.
Sanctions against Iran have never been as suffocating as those imposed on Iraq after it invaded Kuwait in 1990 but they do inflict damage. Transferring money in and out of the country is a problem. One foreign student complained how she had spent weeks trying to bring a few hundred dollars to Tehran. Sellers of luxury goods such as carpets and caviar are once more victims of a US embargo reimposed last year. On the other hand one result of the crisis is to increase Iran's oil revenues to $80bn over the past year.
More importantly, Iran is suffering from a shortage of the petrol that it is no longer allowed to import because of sanctions. The government has limited the amount sold to car owners at a subsidised price. It has also diverted some of its petrochemical plants to making petrol, claiming the country is self-sufficient. But the petrol produced is low quality and highly toxic, ensuring that Tehran's 15 million people live in one of the most highly polluted places on earth. On some days recently it has been difficult to see the snow-covered mountains just to the north of the city.
In almost every way recent Iranian experience differs from that of most of the Arab world. The "revolutions" in Libya, Egypt, Syria and Iraq in the 1950s and 1960s, though they initially might have had popular support, were military coups. In contrast to its neighbours Iran had a genuine revolution, followed by the eight-year-long Iran-Iraq war, which has meant that Iranian politics are conducted with all the hatred and bitterness of an armed conflict.
President Ahmadinejad, whose own career was shaped by his experiences in the Iranian Revolutionary Guard Corps (IRGC), sees his electoral opponents as potential traitors plotting against the Islamic Republic. He has the advantage over Arab rulers that, even though the vote for him in 2009 may have been fixed, he and his government have a core of militant and fanatical supporters. Moreover, this support is organised in para-state bodies such as mosques, the IRGC and the much feared Basij militia.
Political and religious differences in Iran often run along class lines. Supporters of the Greens in Tehran admit that they have never expanded their support base to the urban and rural poor, unlike protesters in Egypt and Tunisia. This does not mean that reformers do not pick up votes among the poor – but their militants tend to be the educated and the middle class.
One professor at a university in Tehran describes how, during the 14 February protests this year, students belonging to the Basij tried to stop fellow students joining the Green demonstration. He said: "The Basij only have about 10 per cent support at the university, but maybe 40 per cent or even a majority outside."
Repression is likely to prevent protests gathering support on the street though there is evidently a body of courageous activists willing to take great risks. But opposition postings on YouTube mainly show police and basij while the most dramatic pictures of protesters show young men wearing shirts without coats, an unlikely choice of clothing in the chill air of Tehran. The pictures look as if they may date from the mass demonstrations in the summer of 2009.
The clamp down on street protests is accompanied by the government doing everything it can to control Iranian and foreign media. The flourishing world of reformist newspapers has disappeared. Foreign television broadcasts in Farsi are disrupted. On the internet many sites cannot be obtained. Foreign journalists are largely excluded from the country and Iranian contributors to the foreign media are tightly controlled. Censorship is not complete but the mutually supporting relationship between protests and the media seen in the Arab uprisings is unlikely to flourish.
Many militants who supported reform in 2009 have now moved abroad. Opposition websites put out news about demonstrations, arrests and imprisonment. But the regime looks as if it has successfully outlasted the furious reaction to the 2009 presidential election, that so many Iranians regard as fraudulent.
Part of the strength of protests then was that the Iranian establishment, including the clergy, were divided. Powerful traditional power brokers such as Ali Akbar Hashemi Rafsanjani, who has so often been accused of corruption, supported the opponents of Mr Ahmadinejad. Now these establishment figures are being forced to break with the Greens if they want to remain within the ruling elite.
US diplomats are hopefully spreading the word that the success of the broadly secular uprisings in the Arab world shows that Iran's Islamic revolution is out of date. But Iranian leaders will be happy enough that the political landscape of the Middle East has so unexpectedly and dramatically changed in Iran's favour.
The marginalised opposition
* The presidential candidate in 2009 whose defeat by the incumbent Mahmoud Ahmadinejad led to an explosion of rage and mass street protests across Iran claiming fraud.
* The 68-year-old Mr Mousavi, from east Azerbaijan, was a student radical under the Shah and an admirer of Che Guevara. He became prime minister of Iran between 1981 and 1989 and was seen as being on the left of the Islamic movement.
* On the death of Ayatollah Khomeini he left politics and confined himself to architecture, painting and poetry for 20 years. The government says he is under house arrest, while the opposition movement say that he is in fact in jail.
* The 73-year-old reformist cleric was one of the defeated presidential candidates in 2009 and also alleges fraud.
* Twice speaker of parliament, he has remained outspoken as an opponent of the government since the election. He was a candidate for the presidency in 2005 when he alleged that the vote had been manipulated. He accused the government of raping and sodomising opposition activists, causing a scandal within the Iranian political establishment.
* His unexpectedly low vote in the 2009 poll, even in his home province, is cited as strong evidence that the election was fixed.