BEIRUT -- There is one big difference between the Iranian and Russian interventions in the Syrian war to save the hide of their mutual ally, Syrian President Bashar al-Assad. Iran and its Shia allies, most notably Lebanon's Hezbollah, have suffered thousands of men killed or wounded. Russian combat deaths are probably no more than two or three dozen, if that.
On the face of it, there has been no indication that the huge disparity in casualties is causing major friction that might threaten this unusual alliance, a marriage of convenience between two states struggling to become regional superpowers, eagerly exploiting the retreat by the United States, which not so long ago was the ultimate power in the Middle East.
This odd-couple coalition, however, is coming under strain, largely because the two countries' strategic imperatives in Syria are widely divergent and could become even more so.
The Assad regime's recent conquest of eastern Aleppo, held by rebel forces since mid-2012, may be a pivotal point in the Russian-Iranian partnership as it could mark where they part ways in terms of what comes next in Syria.
The fragility of their common efforts in Syria was illustrated in August when Iran agreed to allow Russian strategic bombers to operate from the Islamic Republic's Hamadan airbase against rebel targets in Syria, then cancelled the decision a week later amid a firestorm of domestic criticism for abandoning revolutionary principles by permitting a foreign power to base military forces on Iranian soil.
In regional terms, Assad's second-hand victory in Aleppo, largely paid for with Iranian and Shia blood on the ground, was a triumph for Tehran because it cements the land bridge that it is building between the Islamic Republic across Iraq to Syria and Lebanon to make it the paramount regional power from the Arabian Gulf to the Mediterranean.
Russia supplied the air power, backed with broadsides of cruise missiles from its warships in the eastern Mediterranean, that bludgeoned eastern Aleppo into rubble and opened the way for the battle-hardened fighters of Hezbollah and Shia mercenaries from Iraq, Pakistan and Afghanistan to fight their way into the rebels' last major urban stronghold.
For Russian President Vladimir Putin, victory in Aleppo gave immense impetus to his drive to restore Moscow's international power to what it was before the Soviet Union crumbled in 1991.
It also assured him naval, air and intelligence bases in Syria, the only ones Moscow has outside the Russian federation, with which to challenge the Americans and a weakened post-Cold War NATO.
"Russia's action in Syria is not really about Syria or even about the Middle East. It's about its global role — and eventually [about] a coalition of equals with the U.S.," Dmitri Trenin of the Carnegie Moscow Centre said during a conference on regional security in Beirut in December.
Iran's imperatives are much more regional, reflecting the regime's escalating proxy operations in Syria, Iraq, Yemen, Lebanon and the Gulf to extend Shia control throughout the largely Sunni-dominated eastern end of the Arab world and right what it perceives to be a 1,300-year-old wrong.
Now reports from Syria stress that the Iranians felt betrayed by a cease-fire agreement reached in Ankara by the Russian military and Turkey's intelligence service on Dec. 12 to end the Aleppo fighting and evacuate tens of thousands of civilians and rebel combatants. Within hours, the Iranians sabotaged the deal. The cease-fire finally took effect Dec. 15.
Russia accuses Iranian-backed Shia militias, which suffered severe casualties in the fierce street fighting in and around Aleppo, of breaking the Ankara agreement because it did not embrace Tehran's military and ideological imperatives.
Putin's extensive military support for Assad, including carpet bombing unprotected cities such as Aleppo, underlines his determination to achieve his global objectives by exploiting every opportunity he gets and securing bases that will drive his strategic game plan.
The Iranians want to dominate Syria for their own strategic purposes. The war that erupted in March 2011 gave them the opportunity.
Unlike the Russians, they are buying real estate and businesses across Syria and encouraging Assad's ethnic cleansing process under which his minority Alawite regime forcibly displaces the majority Sunnis and minorities such as the Kurds to the outer fringes of modern Syria, leaving Assad and his Shia-leaning cronies ruling a rump state in the western and central regions.
This accommodates Iran, which wants to maintain its supply line through Syria to Hezbollah in Lebanon for a possible confrontation with Israel.
Assad and his cronies have a lot to thank Russia and Iran for but preventing the collapse of the Damascus regime has come at a hefty price — one that is likely to increase.
Diplomatic and Arab sources say Assad and his inner circle no longer call the shots and formulate policy, particularly regarding defense and security, which are largely in Russian and Iranian hands.
After Aleppo, Iran is emerging as the real winner.
Moscow mostly dictates political policy because, unlike Iran, it is a permanent member of the U.N. Security Council, which means it regularly vetoes any council effort to secure a diplomatic solution to the Syrian carnage that does not meet with Putin's game plan.
The Iranians dominate military policy by dint of their army of Shia militiamen as well as sizable numbers of Islamic Revolutionary Guards Corps and so-called military advisers.
It was Maj. Gen. Qassem Soleimani, commander of the IRGC's elite al-Quds Force, who forged the military alliance with Moscow in Syria in July 2015, two months before Russia sent in its air force to save Assad's crumbling regime dominated by the minority Alawites.
Lebanese analyst Hanin Ghaddar noted at the time that this alliance was "a temporary one. It's an alliance over Assad. Not Syria...
"In Iran's view, Syria is not a state. It's just part of the Iranian plan. Fundamentally, what Iran wants in Syria is what it has in Lebanon — weak, ineffective state institutions incapable of making decisions without the approval of their patrons," she observed.
"Unlike Tehran, Moscow is not interested in changing democracy or in maintaining the Shia-Alawite corridor. Moscow does not want to see Assad go and then be replaced by Soleimani."
Iran is working with Assad's regime to forcibly move Syria's majority Sunnis and other groups at odds with Assad's rule out of Damascus and Syria's strategic heartland, the Mediterranean coast and the border with Lebanon, to establish what has become known as "Useful Syria."
Iran has even brought in Shia settlers, including the families of foreign fighters deployed in Syria by Tehran from outside Syria, to populate areas the regime considers vital to its long-term interests and expansionist strategy in the region.
The IRGC and Iranian entrepreneurs in Syria have been allowed by the Damascus regime to buy businesses and large tracts of property in and around the capital and in other parts of "Useful Syria" to bolster the plans to secure Shia control.
This indulgence by a grateful Assad and his inner circle likely means that Iranian companies, particularly the IRGC's powerful business empire, will be handed lucrative contracts when the massive post-war reconstruction gets under way.
The Iranians "are building a force on the ground that, long after the war, will stay there and wield a strong military and ideological influence over Syria for Iran," said analyst Philip Smyth, a specialist on Shia militias with the Washington Institute for Near East Policy.
"And there's not much Assad can do to curb the rising influence of these groups, even though Syrian officials are clearly concerned about this because the militiamen are literally preventing the overthrow of his government."
From that perspective, Russia's expanding role in Syria could serve as a counterweight to Iran's burgeoning presence in a state once seen as a bastion of the Arab world, a legitimacy that Assad is desperate to regain.
Indeed, the Assad dynasty's legitimacy rested on its portrayal of itself as an Arab nationalist regime. It is this Sunni-dominated political order that Shia Iran seems bent on eradicating.
"Some observers are reading the Russian intervention as an attempt to pre-empt the total 'Iranization' of the Syrian state, as much as it's an attempt to rescue the regime," observed Faysal Itani of the Atlantic Council's Middle East center in Beirut.
This article originally appeared at The Arab Weekly.