LONDON From Los Angeles to Paris to Tehran, disparate opposition groups with little in common but an aversion to Iran's clerical leaders are struggling to extract political gains from an escalation in Western sanctions.
Numerous dissidents have hailed Western agreement on tougher measures to compel the Islamic Republic to rein in its nuclear programme, but translating the upbeat mood into renewed opposition activity will not be easy, Iran experts say.
Internally, opposition forces are at a low ebb following the bloody suppression of a loose reformist street protest movement they mounted in 2009.
Iran's factionalised clerical authorities may be driven by their own disputes, but the security apparatus has a tight grip on domestic dissent and its leaders are under house arrest.
Overseas, the complexity of the dissidents' task has roots in the opposition's very diversity: The communities of monarchists, communists and liberals and others can agree on little beyond ending the three-decade rule of Islamist clerics.
Discord extends to the utility of sanctions as an instrument of leverage: Exiled groups tend to favour them. But dissidents at home are less enthusiastic, arguing that the measures will hit the middle class from which the 2009 protests sprang.
One thought found among oppositionists on both sides of the internal-external divide is the fear that the curbs could raise regional tensions and trigger a devastating conflict.
"If you corner a cat, you should expect it to show its claws," said a leading reformist politician, who asked not to be named due to the sensitivity of the matter.
"If the authorities feel that they have no alternative, they might do anything, including interrupting shipments of oil."
"Don't forget that some hawks in Iran favour a war, to unify the people and also to divert attentions from their shortcomings. Whether they will reach their aim of unifying people, I have doubts but historically, Iranians never back foreign invaders."
"GAME HAS CHANGED"
On New Year's Eve, U.S. President Barack Obama signed into law the toughest financial sanctions yet against Iran, which if fully implemented could make it impossible for most countries to pay for Iranian oil. The European Union, which still buys a fifth of Iran's 2.6 million barrels per day of exports, is expected to announce an embargo this month.
Tehran has responded to the sanctions with threats to international shipping that have frightened oil markets.
Some opposition figures appear elated at the turn of events.
"Things are happening which are unbelievable. This is not the same as before, this is something else," said Manouchehr Ganji, 80, who was a minister of education under the late Shah of Iran, Mohammed Reza Pahlavi.
"The name of the game has changed... In the past, they (Iranians) have become accustomed to having bananas - Iran doesn't produce bananas - and accustomed to having pineapple, to having all the things you can find in the world. They could have it because of the oil money," said U.S.-based Ganji.
For the sanctions now to be effective, the governments of the United States and Europe must "make it known to the Iranians that they understand the lot of Iranians, and they understand the harsh situation they are living in," Ganji said.
"It all depends on how they are going to present it to the Iranian people," he added.
The French-based National Council of Resistance of Iran (NCRI), which has followers across Europe and the United States, supports the tougher sanctions but argues that only "regime change" will prove to be an effective policy.
The NCRI was responsible for arguably the most influential opposition move in years when it became the first group to expose Iran's covert nuclear programme in 2002.
It says it has huge backing within Iran although analysts say its support is very hard to gauge.
Its leader Maryam Rajavi told Reuters the tougher sanctions "should have been undertaken a long time ago."
She suggested the Iranian authorities were bluffing about closing the Hormuz Strait and only engaged in this tactic "because they are confident of the West's indecisiveness."
Others, such as U.S.-based Ali Shakeri, 63, are sceptical about the usefulness of economic curbs.
"CURBS HURT THE AVERAGE CITIZEN"
The Iranian-born peace campaigner and businessman says sanctions especially hurt the average citizen. He said: "Any society without a middle class, with the oppressed people and the elite of billionaires, is not going to end up to any democracy."
"It's going to end up to a dictatorship or chaos."
Shakeri was jailed in Iran on security-related charges in 2007 when he went to visit his ailing mother. He was held in jail for 140 days, and was told that one of the charges against him was that he had hosted Iranian Nobel Peace Prize winner Shirin Ebadi at the University of California, Irvine.
"The unfortunate situation between the United States and Iran has hurt us more than we can imagine," Shakeri said. "That's why a person like me, I'm pushing for dialogue, diplomacy and an economic relationship."
Shakeri said that he believes Iran will not close the Straight of Hormuz because that is the country's "lifeline."
Others disagree, saying if Iran is attacked militarily, all bets are off.
Muhammad Sahimi, a professor of chemical engineering at the University of Southern California and a frequent media commentator on politics in his native Iran, said that despite Iran's "sabre rattling," he does not believe the country will close Hormuz, in part because its major oil customer China gets shipments through that waterway.
But if Iran is attacked militarily, it will seek to close the Straight of Hormuz, he said.
He said Farsi-language satellite television stations based outside Iran have little political sway within the country itself. Iranians are more likely to get their news from watching and listening to BBC broadcasts, he said.
Sahimi supports Iran's efforts to obtain nuclear capabilities to generate electricity, but as a member of the Union of Concerned Scientists he said that he would oppose any effort by the country to develop nuclear weapons.
Iran's dissidents have undeniable potential clout.
Collectively opposition sympathisers in the diaspora, especially affluent exiles based in California, could wield ample power through the pocketbook. And in cyberspace, Iranian "Green Movement" anti-government protesters in 2009 helped pioneer the kind of influential social media skills that were adopted to telling effect in the Arab Spring revolts of 2011.
Iran's factionalised power structure, too, might seem to offer openings: Conservative hardliners opposed to President Mahmoud Ahmadinejad's economic policies are openly manoeuvring against him ahead of elections in 2012.
SANCTIONS' EFFECT "VERY GRADUAL"
But for the moment, some diplomats and analysts say, Iranian opposition activists find themselves little more than observers of a drama whose outcome they can as yet do little to influence.
Their hope is that the pressure widens fissures in internal power struggles in such a way that the gap between ruler and ruled widens. That might enable activists to revive the sort of opposition energies last seen at work during the 2009 protests.
But one fear is that more sanctions will rally Iranians around the flag. Some dissidents say that until internal dissent is re-energised, the possibility of change will remain slight.
Reza Pirzadeh, 43, President of the Paris-based Iranian Green Democratic Congress, said the latest sanctions proposal made it even more important to speed up the process of creating a credible democratic alternative in Iran, but that the process had to come from within and could not be dictated by exiles.
"Iranians will only be able to go onto the streets when they know that there is an alternative," he said.
"They did that 30 years ago under the slogan 'the Shah must go' and everything will be better but today everybody is demanding they know exactly in which direction we are heading before getting rid of this regime, which is why we have to be as clear and transparent as possible."
UK-based Aliasghar Ramezanpoor, a deputy culture minister in Iran between 2001 and 2003, said the sanctions were having an impact but "I think these sanctions will not contribute directly to a change in Iran's government."
"In reality it can be said that the sanctions are shortening the life span of the regime although they won't change it directly. The effect is very gradual. The government knows how to get around the sanctions to preserve its power."
(Reporting by John Irish in Paris, Yeganeh Torbati in London and Alex Dobuzinskis in Los Angeles; Editing by Giles Elgood)