In the event Iran's moderates come out on top in this post-election turmoil – an outcome few are counting on – the balance of power in the region could shift substantially, potentially putting Arab states allied with the US on the back foot.
"Any closer relationship or dialogue between Iran and the West would give them [Iranian leaders] more influence, [an] upper hand in the Arab world and the Gulf region, and that is a threat to the interests of Arab countries," says Essam El Erian, who heads the political affairs section of the Muslim Brotherhood.
Arab states are already worried about Iran's growing influence and suspect the ultimate aims of its nuclear program. In recent years, that has provided common ground with the US, which shares those concerns. That alliance of the US and Arab states is opposed by an "axis of resistance" composed of Iran, Syria, and militant allies Hezbollah and Hamas – in Lebanon and the Palestinian territories, respectively.
But the lines between those two camps could blur as Iranians challenge the regime's firm stand on an election widely seen as fradulent and President Obama launches full-force into his Middle East policy.
Syria – Iran's only Arab ally – is already drawing closer to normalizing relations with the US, with reports Tuesday that the Obama administration has decided it will send an ambassador back to Damascus after a four-year hiatus.
If political change in Iran meant that Iran's support for Hezbollah and Hamas were lessened, meanwhile, the militant groups' leaders " would be negotiating for their own safety," says Hisham Kassem, founder of the independent Egyptian daily Al Masry Al Youm.
Either way, Iran will move forward with nuclear program
Political scientist Thomas Mattair is leery of speculating on what will happen in Iran. But whoever comes out on top in the country's current domestic battle, drastic changes in its foreign policy and behavior should not be counted on, says Mr. Mattair, author of the recent book "Global Security Watch: Iran", which analyzes the country's foreign policy.
"As all this unfolds they're still moving forward with their nuclear program, I very much doubt they've paused, and all of the political leaders favor the nuclear program," he says. "In the medium- and the long-term Iran is so big and has such a large armed force that, no matter what happens, these states will still be seeking security guarantees from the US and will be worried about Iran."
What happens if the Iran's hard-liners win a decisive victory? "If the regime doesn't compromise with its opponents, if it hardens, then the potential for military strikes by the US would increase, and that would alarm Saudi and the [Gulf] states as well because Iran has all kinds of asymmetrical abilities in those states, some of which are home to US forces."
Why Iran's turmoil could boost Arab support of Iraq
One area in which important regional change could come is if the US and its allies can use the ongoing turmoil in Iran as an argument to regional allies such as Saudi Arabia that they should recognize and work with the Iraqi government of Nouri al-Maliki, a Shiite whom they have been reluctant to work with because of their perception he's close to Iran but who is, nevertheless, an Arab like them.
"As we withdraw from Iraq, we have one more argument to make to Saudis' and the other [Gulf] states about why it's so important to stabilize Iraq to limit Iran's influence," he says. "With Iran going through this kind of turmoil, you can present it to the Saudis as an opportunity: 'Here's a chance to take advantage of this moment.' "
Indeed, US Defense Secretary Robert Gates urged Arab states on Tuesday to rally around Iraq for precisely that reason. "The embrace of Iraq by its fellow Gulf states will help contain the ambitions of Iran," he said.