But as President Obama and Israeli Prime Minister Benjamin Netanyahu meet in Washington today to discuss the Iran nuclear threat, many in Israel argue that Tehran may end up one of the biggest losers of the upheaval.
Embattled Syrian President Bashar al-Assad, a key Iranian ally who faces a year-long uprising against his regime, has long been the linchpin of a regional alliance led by Tehran and including Hezbollah in Lebanon and Hamas in Gaza. Both groups, with armed militants on Israel's borders, are seen as proxies that Iran could use to retaliate against an Israeli strike on its nuclear program.
If the uprising succeeds in toppling Mr. Assad, the so-called "axis of resistance" would suffer a blow because the removal of a friendly regime in Damascus could end the weapons-supply link from Iran to Lebanon.
The axis of resistance already received a lesser blow in recent weeks, when Hamas abandoned its long-time patron Mr. Assad and relocated its headquarters from Syria to Egypt and Qatar, two Sunni states with stronger ties to the West.
"[The Arab Spring] changes the trend from an ascendency of Iran and its allies and its cronies to the decline and fall," says an Israeli diplomat who was not authorized to speak about the topic on the record. "Everybody was talking about the Shiite crescent. The Shiites are still there, but the Iranian dominance is flailing. They still wield influence over Iraqi Shiites, and Hezbollah, but there’s going to be a missing link if Assad falls."
To be sure, even though Iran's influence appears to be waning, Israelis worry that if Iran got a nuclear weapon, it could quickly regain that lost ground and be better able to project its power through the region.
That fear has added urgency to Mr. Netanyahu's efforts today in Washington to persuade Mr. Obama to define clear "red lines" for Iran's nuclear program.
Also tempering Israeli optimism is the fear that a power vacuum in Syria could destabilize the country and perhaps neighboring Lebanon as well in the near future. Israeli military and intelligence officers say they are extremely concerned that if central authority in Syria were to devolve, Hezbollah might transfer some of Syria’s non-conventional arsenal – including chemical weapons – into Lebanon.
'Syria is the key to Iranian power'
In the early months of the Syrian revolt, Israeli officials remained tight-lipped, fearing rising instability on the normally calm border with the Golan Heights and facing uncertainty about who would replace Assad. Concern that Israeli calls for Assad’s ouster would undermine the Syrian opposition also deterred Israelis from speaking up.
But now, as the West and much of the Arab League have united in isolation of Syria, Israelis have become more vocal in asserting that Assad’s downfall is inevitable. Last month on a state visit to Japan, Israeli Defense Minister Ehud Barak predicted that it would be a matter of weeks before his demise.
Mr. Obama also mentioned Assad's downfall and Iran's isolation in a speech yesterday to thousands of Israeli supporters at the annual conference of the American Israel Public Affairs Committee (AIPAC) in Washington: "Iran is isolated, its leadership divided and under pressure. And by the way, the Arab Spring has only increased these trends, as the hypocrisy of the Iranian regime is exposed, and its ally – the Assad regime – is crumbling."
Israeli experts say that although the Syrian revolt is directed first and foremost at Assad’s minority-led Alawite regime, protesters and opposition groups have taken note of Tehran’s and Hezbollah’s active involvement in coming to Assad’s aid. Just six years after Hezbollah won the hearts and minds of the Arab world for fighting Israel, its flags – and those of Iran – are being burned in Syria, says Eyal Zisser of Tel Aviv University.
"Iran became extremely unpopular in Syria because of its support for Bashar in Syria," says Mr. Zisser, who has written several books on Syria.
He says that if Assad’s regime were to collapse, it would be replaced by a Sunni government that would "no doubt" sever its alliance with Iran and Hezbollah.
Ephraim Halevy, a former director of Mossad, the Israeli intelligence and special operations agency, said at a conference Feb. 2 that Israel should view the turmoil in Syria as the Achilles' heel of Tehran.
“What will happen in Syria will determine to a large extent the future of the Middle East,” he said. “Syria is now at the hub. Syria is key to Hezbollah. Syria is key to Iranian power.”
Hamas, a Sunni Palestinian militant group which has been armed and financed by Iran since taking control of the Gaza Strip in 2007, has been caught for months in between its patrons in Syria and Iran, and the Palestinian masses who by and large sympathize with their Sunni brethren fighting Assad's regime.
The organization has been forced to leave its Damascus headquarters, which managed ties with Iran. But Hamas's moves aren't purely logistical. Hamas leader Khaled Meshal, considered a hard-liner during the years he was based in Damascus, has recently hinted at an ideological change within the movement, talking up nonviolent protest against Israel and courting reconciliation with the Western-backed Palestinian Authority – both moves that Tehran had opposed.
But Hamas has not altogether abandoned Iran. A recent visit to Iran by Gaza leader Ismail Haniyeh was seen as an effort to reset ties with Tehran in the wake of the Syrian upheaval.
Both sides "need to reorganize and reestablish ... the links between Hamas and Iran," says Yoni Figel, a counterterrorism expert at the Herzliyah Interdisciplinary center and a former Israel army colonel.
But more important for Iran is to try to keep Assad in power, since its influence could well decline if he is ousted.
"Iran will do its utmost to postpone [regime change] as much as it can, and maybe it will be able to revive Assad," says Mr. Figel. But "if the regime collapses, this is a new strategic situation."