Demonstrations in Syria are played down by Iran while other Arab-world uprisings and protests are hailed as an 'Islamic awakening'
Iran is keeping a nervous eye on the growing unrest in Syria, where the Assad regime has been its staunchest Arab ally through three often-turbulent decades in the Middle East.
Tehran's ability to project its power in the Arab world would be greatly reduced if Syria plunges into turmoil or its president is replaced by a less-friendly leader of a Sunni-dominated government.
"It would be quite a blow to some of the Islamic Republic's strategic interests," said Trita Parsi, president of the Washington-based National Iranian American Council.
Iranian officials currently appear confident the Syrian authorities will be able to crush the peaceful unrest which has stirred the country.
To ensure that outcome, Iran is sending Damascus material support to crack down on protesters, American officials claimed this week, while Hillary Clinton accused Iran of "hypocrisy".
The US Secretary of State said Tehran was trying to align itself with some of the Arab popular uprisings, while trying to thwart democracy movements at home and in Syria.
In turn, Tehran maintains that Western powers are stoking Syria's unrest to undermine Iran because it supports President Bashar al Assad's "resistance" against Israel.
Some Iranian hardliners have also accused Saudi Arabia and Jordan, key regional US allies of stirring the Syrian pot for the same reason.
Tehran has until now mostly welcomed the changes in the emerging new Middle East, viewing them as blows to the US and gains for its own geopolitical ambitions.
Iran is also enjoying windfall oil revenues resulting from the regional upheaval, a valuable buffer against US-driven sanctions.
While Iran would be loath to acknowledge it, one loss on its strategic balance sheet is its intensifying cold war with Saudi Arabia, primarily over the unrest in Bahrain, which is deepening Tehran's isolation in the Gulf.
Set against that is a significant gain: the seeming readiness of Egypt's new leadership to restore ties with Tehran after a 31-year rupture. Riyadh and Washington had valued Hosni Mubarak's Egypt as a key Sunni bulwark against Iran.
"If you look at the chessboard as a whole, many of the developments are viewed positively by Iran," Mr Parsi said. "But if the Assad regime falls, the picture could change dramatically."
Syria has been the portal for Iran to extend its reach into the Middle East and a vital connection to Lebanon's Iranian-backed Hizbollah movement, which gives Tehran a proxy presence on Israel's northern border.
Syria and Iran also support the militant Palestinian group Hamas in the Gaza Strip. And Tehran has billions of dollars worth of investments in Syria.
On the face of it, Tehran and Damascus make unlikely bedfellows. Non-Arab Iran is a hardline Shiite Islamic republic. Syria is a staunchly secular Arab state where the majority of the population is Sunni, although Mr Assad's family and the bedrock of his regime are from the minority Alawite sect, an offshoot of Shiite Islam.
The Iranian-Syrian alliance is one of convenience, but has been remarkably enduring, based on making common cause against mutual enemies, primarily Saddam Hussein's Iraq and Israel.
It helped that Tehran and Damascus do not have competing interests. Syria wants to be the "beating heart of Arabism", while Iran vies for leadership of the Islamic world.
The Syrian unrest has been deeply embarrassing for Iranian officials domestically. When the Arab revolts began, their spin was that only governments closely allied to the US - "American stooges" - would be challenged by their peoples.
Syria, therefore, was safe, as is Iran itself because, the argument went, their rulers are in tune with the popular anti-American pulse at home and on the Arab street.
"That narrative has clearly lost its credibility because being on bad terms with America is obviously not enough to ensure domestic stability," said Meir Javedanfar, an Iranian-born analyst in Israel.
However, Iran's concern over the Syrian crisis should not be overestimated, some experts say. "There is nothing in the Iranian political discourse that suggests Iran is worried about Assad's ouster," said Farideh Farhi, an Iran specialist at the University of Hawaii. "To be sure, like the Americans and the Israelis, the Iranians are concerned about instability in Syria, but they fully expect that Mr al Assad's regime will follow the Iranian example in crushing dissent," Ms Farhi added in an e-mail.
Even if Mr al Assad were toppled, few would try to predict the shape of any new Syrian government. So it cannot be assumed that his successors would relinquish Syria's alliance with Iran, or its support for Hizbollah.
Both are valuable cards that have enabled Damascus to punch above its weight in the region and beyond.
But Tehran, allegedly, is taking no chances. Washington said on Thursday there was "credible information" that Iran has been helping Syria to quell the protests.
The accusation followed a Wall Street Journal report that Iran has provided Damascus with crowd control equipment and technical assistance to monitor internet and cellphone communications used by opposition groups to organise protests and report abuses.
Iran was sharing lessons learnfrom its own 2009 post-election clampdown on the mass demonstrations that erupted after President Mahmoud Ahmadinejad's disputed re-election, a US defence official told the journal. Tehran and Damascus denied the accusations.
The Syrian protests initially received little media attention or official comment in Iran.
In stark contrast, Iranian state-controlled media have given wide coverage to the uprisings elsewhere in the Arab world, trumpeting them as "Islamic awakenings" against Western-backed despots, purportedly inspired by Iran's 1979 revolution against the Shah. The reports ignored the facts that the protests are mainly secular and driven by demands for democracy.
Opposition websites, however, have carried international news reports detailing the demands of Syrian pro-democracy protesters and the numbers killed.
And a Tehran University politics professor, Sadegh Zibakalam, wrote recently that Arab countries "have the right" to ask Iran why it is so much more concerned about the killing of protesters in Bahrain than the deaths of many more in Syria. And he suggested that Iran's tirades against countries such as Saudi Arabia are unnecessarily alienating Tehran in the Arab Middle East.
Iranian officials broke their silence on Syria's protests only when their persistence and scale became impossible to ignore. Then, predictably, they portrayed them as Syria has done: as small, sporadic and fomented by the West to help Israel.
Mr Ahmadinejad proclaimed on April 4 that "America and the Zionist regime want to weaken Syria's resistance by creating discord between the Syrian government and the Syrian nation."
A foreign ministry spokesman added that "mischievous" Western powers are also trying to hurt Iran through its alliance with Syria because of Tehran's similar "resistance" to Israel.
Paradoxically, Iran's concerns about Syrian instability are shared by Tehran's two main enemies, the US and Israel, albeit for vastly different reasons.
While the Assad regime is a sworn enemy of Israel, it is a known one. Their joint border, straddled by the Israeli-occupied Golan Heights, has hardly seen a shot fired in anger for nearly four decades. Israel is adopting the "attitude of better the devil you know than the one that you don't," Mr Parsi said.
Scott Lucas, an expert in Iran and US foreign policy at Birmingham University in England, said the US is also "extremely worried" that Mr Assad could be toppled because "they have no clue what would happen after him".
While his ouster would be a blow to Iran, which the US would welcome, it would be outweighed by other concerns in Washington.
Mr Lucas said in an interview: "The whole question of a realistic settlement in the Middle East is premised on having stable regimes that can deliver that - and Assad's was one of those regimes."