Iran has rejected allegations from Britain and the United States that it is helping Syria crack down on domestic opposition with advice, equipment, and training. Iran remains a key Syrian ally, with the two governments finding common ground on such issues as Israel, Lebanon and Iraq.
U.S. Secretary of State Hillary Clinton accuses Iran of supporting the Syrian government in what she calls its vicious assaults on peaceful protesters and military actions against its own cities.
The charge follows similar concerns from British authorities, including Foreign Secretary William Hague who said there is credible evidence of Tehran giving Syria aid to suppress dissent.
The Iranian foreign ministry denies any involvement in the Syrian crackdown, countering that it is other countries, in particular the United States and Israel, that are supporting what it calls "terrorist" actions in Syria.
Spokesman Ramin Mehmanparast says the foreign criticism is part of a plot against the "line of resistance" against Israel. That anti-Israeli line informs much of Iran's response throughout the past months of political protests in the Arab world. Tehran has sided for the most part with the popular uprisings, but draws the line when it comes to Syria.
Mounzer Sleiman is the director of the Center for American and Arab Studies.
"Iran views the struggle in the Middle East in terms of two camps, the camp of resistance, whether it is from the Lebanese resistance, the Palestinian resistance and the popular support throughout the Muslim world and the Islamic world and officially for Syria and Iran as governments," Sleiman said.
But Sleiman says Syria has no need for material help from Iran, dismissing recent Western accusations as "nonsense."
"Of course, Iran would like Syria to be safe and to be stable and to continue the role it has been playing geo-strategically in the Arab world and to maintain the alliance with Iran, because Iran and Syria are the subject of isolation by Washington, by Israel, by the Europeans and by others," Sleiman said.
Despite the increasing pressure and isolation, both Iran and Syria got a boost this week when a new government emerged in Lebanon dominated by Hezbollah, the political and militant group backed by both.
But such victory comes at a price. Already the Syrian government's alliances have prompted Syrian protesters to burn the Iranian flag and pictures of Hezbollah leaders.
The Center for American Arab Studies' Sleiman says this is especially true among conservative Sunni Muslims in the minority Allawite-led country.
"They see the situation in terms of having the regime supporting Hezbollah or supporting the Palestinian resistance; they see it as something at the expense of Syrian internal domestic progress. And it seems they would like to portray what is happening in terms of sectarian views instead of having it as a nationalist view," Sleiman said.
The Syrian government has also tried to play up the sectarian angle, an apparent bid to undermine the political demands of the protesters. But it risks becoming true: the more brutal the crackdown grows, the more frequent are reports of a growing Sunni-Sh'ite divide.
Iran's other interest in Syria is also likely to foster discontent: Iraq, which is also riven by sectarian conflict. The chairman of the Gulf Research Center, Abdulaziz Sager, says Tehran relies heavily on Damascus to extend its influence over their common neighbor, and beyond.
"We have seen Syria paying a lot for the Iraq situation without winning any benefit on Iraq. The importance of the regime in Syria is acting by proxy on behalf of the Iranian policy in there, in the Levant in general, but also very specifically on Lebanon and Iraq. And, at the same time, in case in the future, Iran again decides to go into any confrontation by proxy with the Israelis like Hezbollah did in 2006, that is also a possibility we are going to see," Sager said.
In Sleiman's words, such costs do not outweigh the benefits of Syria holding on to its current course and current allies, no matter how strong the pressure from the West or even the United Nations.
"The regime has many centers of positive elements that support this strategic position, the geo-politic position. And that means to maintain alliances with the resistance in Lebanon, with Palestine and relations with Iran. So, I don't think the regime is going to abandon and accept this kind of pressure, especially if there is a control of the security situation internally," Sleiman said.
Sleiman notes that Syria weathered previous pressure from the West to change its behavior, during the Iraq war. Whether the current internal pressures are enough to tip the balance is what both the opposition and Syria's supporters are waiting to see..