The imminent demise of the Bashar al-Assad regime in Syria has become such an article of faith among many American pundits that most have come to discuss the subject as no longer a matter of if, but merely when, his fall will occur. Unfortunately, for Western talking heads as well as President Obama, who has also predicted imminent regime change in Damascus, Assad has preferred to ignore their advice and instead stick to what his family has always done best: slaughter any and all domestic foes. After watching the fall of dictatorial regimes in Tunisia, Egypt and Libya, the assumption was the logic of the Arab Spring would inevitably force out the Syrian member of a rapidly diminishing club of Arab autocrats. Few in the West believed Assad could survive. But it appears there was at least one group of observers who may have pegged the Syrian as a keeper: his Iranian allies.

The news that a pair of Iranian naval vessels just left a Syrian port and are now heading home through the Suez Canal ought to have brought home the fact that the Iranian ayatollahs may understand their client better than Western editorial writers. Combined with the decision of Russia to boycott a diplomatic effort aimed at bolstering Assad’s domestic foes, it is now clear that Syria’s two major foreign sponsors have not given up on the regime. Unlike Westerners who simply took it for granted that Assad must go, Ayatollah Khamenei and Vladimir Putin have remembered an ironclad rule of history: tyrants fall when they lose their taste for spilling their people’s blood, not when they loosen the reins.

While the Pentagon was saying it had no knowledge of the Iranian ships ever docking in Syria, the brazen dash through the Mediterranean by Tehran’s mariners may have been more than just a morale boost for Assad. The ships, which reportedly consisted of a supply ship and an accompanying destroyer, may have delivered vital munitions to the Syrian security forces just as they were in the process of leveling the opposition stronghold of Homs.

Though defections from his army are a lethal threat to Assad, so long as he retains the loyalty of most of his regime’s security forces, the belief that his fall is inevitable is more a matter of wishful thinking than hardheaded analysis. Assad understands the stakes in the fighting in the streets of Homs and other cities where dissent has flourished is a life and death matter for him and his family. Moreover, it is often forgotten that unlike other dictatorial regimes where military elites can easily switch sides, many, if not most, of Assad’s praetorian guards don’t have that option. Since Bashar’s father first seized power in 1970, the government there has always been as much a sinecure for the Alawite minority to which his clan belonged as it was for the Assad family. The fate of the Alawites in a post-Assad Syria will be difficult, and that gives the many members of this group in positions of power within the army and security forces the same motive for hanging on no matter what the cost.

Iran also has much to lose if their Syrian ally falls, so it is to be expected it will do all in its power to help him prevail. With Russia and China prepared to prevent the United Nations from even condemning Assad, let alone sanctioning support for the opposition, that leaves the opposition looking to Europe and the United States for help. Even though Senators John McCain and Lindsey Graham voiced their support for arming the Syrian rebels over the weekend, it isn’t likely that President Obama or the European Union will follow the same pattern that led to intervention in Libya last year as Qaddafi tottered, despite the fact that the situation was far less desperate than the human catastrophe unfolding in Homs.

The Arab Spring led many Westerners to believe that a paradigm shift in which murderous regimes could no longer get away with atrocities had rendered men like Assad obsolete. But Iran may have figured out that as long as Assad is willing to go on killing his countrymen, there is no reason to assume he can’t hold onto power. That’s an important lesson Western diplomats and leaders like President Obama–who have also underestimated Iran’s own willingness to abandon its nuclear ambitions–should learn.