As the situation in Syria continues to deteriorate with the collapse of the Assad regime becoming increasingly more imminent, further direct intervention by Iran in the Syrian conflict in an effort to save the regime should not be ruled out. For Iran, the Assad regime represents the linchpin to their regional hegemonic ambitions and as such, preserving the regime is central to safeguarding Tehran's axis of influence, which encompasses Syria, Iraq and Lebanon. Direct Iranian involvement in Syria, while a given, further aggravates the already volatile situation in the Middle East. The question is: when will the Western powers led by the US, the Arab states, Turkey, and Israel take the necessary and credible steps to force Tehran to stop meddling in Syria's internal affairs and prevent it from playing a direct role in an effort to quell the Syrian uprising?

Having already sent military advisers along with members of Iran's Revolutionary Guards disguised as pilgrims and pledging firm support for the Syrian government, it is hard to imagine that, left to its own devices, Tehran will stay idle in the face of Assad's imminent demise. Should Iran decide to further deepen its involvement in Syria it would be based on long-term considerations rather than an aim to achieve an immediate advantage. Indeed, from the Iranian perspective, regardless of how the crisis in Syria may unfold, Tehran is determined to maintain its influence, as the loss of Syria would represent a colossal defeat and severely weaken Iran's hold on the "Shiite Crescent" that extends from the Persian Gulf to the Mediterranean. Thus, Tehran may conclude that however risky its involvement may be, without taking such risks it will not only be marginalized in Syria but could ultimately doom its ambitions to remain a significant regional contender, if not the region's hegemon.

Whereas until recently Iran tried to obscure its involvement in Syria, in the past few days Iranian lawmakers called on their government to tell the Iranian public why Syria under Assad is of strategic importance. Ahmad Reza Dastgheib, Deputy Head of Iran's Majlis Committee of National Security and Foreign Policy, said: "We should make all our efforts to prevent the Syrian government from falling." In a further indication of Iran's concerns over the future of the Assad regime, it has dispatched high level officials including Saeed Jalili, the head of Iran's Supreme National Security Council, to assure Assad that Iran will not allow its close partnership with the Syrian leadership to be shaken by the uprising or external foes. Jalili further emphasized that Tehran will do everything in its power to help him effectively deal with the foreign elements who seek the collapse of the regime. Whether driven by deep convictions or wishful thinking, many Iranians still believe that the prospect of Assad's survival remains strong and that with continuing assistance Assad will prevail while Iran safeguards its interests and still emerges as a nuclear power.

This posturing, buttressed by real military and economic assistance, may well be the forerunner of a greater, more transparent and direct involvement of Iran in the Syrian crisis. Tehran is not convinced, as of yet, that the Western powers (led by the United States) will in fact challenge Iran directly should Iran decide to play a more direct and active role to save both the Assad regime and their larger regional interests. Iran knows that the Western powers and Israel, along with Turkey and the Arab states, would like to pull Syria outside of Iran's orbit. To persuade Iran that its continuing involvement in Syria is short-lived, the US, the Arab League (AL), the EU and Turkey must work in concert and adopt coercive, oriented measures to demonstrate to the Iranian Mullahs that this is a no-win situation and that their continued involvement could be disastrous for the regime.

The Arab states' reaction must not be limited to another declaration of outrage as previously expressed by the AL. While the AL might refrain from attacking Iranian forces outright, countries such as Saudi Arabia and Qatar should openly expand their supply of military equipment, financial aid, medical supplies and other necessary provisions to the Syrian opposition in order to shift the conflict to the rebels' advantage. That said, any step taken by the AL short of military action, which in any case is untenable, will not necessarily change the power equation in Syria as Assad will mercilessly use any military means available to him to stay in power. But transparent Arab support will send a clear message to Iran that its involvement in Syria may cost Tehran more than it is willing to pay.

Israel, who would certainly feel directly threatened by the Iranian presence in a neighboring country, should also send a clear warning to Iran, if it has not already: Israel will not hesitate to take any action deemed necessary to protect its national security interests. The implications of the Israeli threat may well be fully understood in Tehran and regardless of how much the Iranian regime boasts about its military prowess, it will no doubt think twice before it fully commits to salvaging Syria with such costs. Iran also understands that should it end up being present on Israel's borders, Israel would be provided with an excuse to attack Iranian nuclear facilities. Of particular concern to Israel are Syria's chemical and biological weapons, which may fall into the hands of militant Islamist groups who may seek to attack Israel at the first opportune moment. Israel should also warn Iran that Israel will hold its leaders responsible for any such provocation and that Iran will suffer horrific consequences.

As I have stated before, Syria has become a battleground between the Shiite and Sunni communities. The involvement of Shiite Iran in Syria would assuredly change Turkey's (which is predominantly Sunni) position altogether. Notwithstanding the ongoing discussion between Ankara and Tehran, Turkey should make it abundantly clear that Iran's direct interference in Syria will not occur with impunity. Regardless of the existing strategic military alliance between Iran and Syria, this does not provide Iran with a license to intervene, particularly because Syria is not threatened by outside powers. Such Iranian interference should prompt Turkey to carve a large swath of land that connects Aleppo with Turkey in which a safe haven for Syrian refugees and an operational base for the Syrian Free Army would be established while, with the support of Western powers, a no-fly zone over the seized Syrian territory would be imposed.

Russia, who has been adamantly against outside interference, will certainly continue to support Iran tacitly but can do little to prevent the countries concerned from acting against Iran should Tehran's involvement become increasingly more transparent. Notwithstanding the fact that Russia would like to maintain Iran's influence in Syria, currently and in the post-Assad era, Moscow's interest would, at a minimum, be served by working with the United States to prevent Syria's biological and chemical weapons from falling into the wrong hands.

Finally and most importantly, having been augmenting its naval forces in the Persian Gulf as part of its preparations to stop Iran from acquiring nuclear weapons and having been morally emboldened by the United Nations General Assembly's resolution (passed with an overwhelming majority) condemning Assad's atrocities, the US poses the greatest threat to Iran. For this reason, Iran is not likely to defy the American warnings, as stated by Secretary of State Hillary Clinton, that the US will not tolerate any power to cross such a red line. For Iran to take the American warning seriously, the United States' warning must not be veiled by political ambiguities, as Iran will not be deterred from aiding Assad militarily unless the threat to them is clear and credible. To that end the US must take decisive measures without necessarily placing military boots on Syrian territory.

In this regard the US should move from debating the need for imposing a no-fly zone to implementing it with the support of Turkey and work with other countries, including Russia and the rebels to safeguard Syria's stockpile of chemical weapons. Moreover, the US must facilitate the supplies of anti-tank and anti-aircraft weapons, and encourage top Syrian officials to defect now with a promise to have a future in the new Syrian government. The US must also make it abundantly clear to the Syrian National Council and the Syrian Free Army that they must work in concert and send a warning to all Syrian minorities that they have a serious stake in Syria's future and only if they work together will they will blunt further Iranian interference and ensure peaceful transition instead of plunging into sectarian war that will tear Syria apart. Short of taking these measures, the United States will risk the opportunity not only to remove Syria from Iran's belly but also forsake the chance of playing a significant role in shaping the new political order in Syria.

The ultimate question is: will Iran gamble by taking such a risk? The answer, I believe, rests with Tehran's paramount desire to preserve first and foremost its own regime, and that may well depend on whether or not Tehran takes the threats of Western and regional powers seriously. This is the time when only action matters. Otherwise, the region will be swept into horrifying conflagration in which every state will be a loser, especially the United States and its allies.