As the Syrian civil war reaches its denouement with the imminent fall of the Idlib enclave—the last stronghold of forces fighting Bashar al-Assad’s regime—Iran’s presence in Syria has reached the top of the American agenda for the Middle East. When US National Security Advisor John Bolton met with his Russian counterpart, Nikolai Patrushev, on 23 August in Geneva, he demanded that Russia persuade Iran, with which it has been collaborating in Syria in defence of the Assad regime, to remove its forces from Syria. Patrushev made it clear that, while Russia wasn’t necessarily opposed to the idea of Iranian troops withdrawing from Syria, it couldn’t force them to leave.

In fact, the pressure mounted by the US (and Israel) has had the unintended effect of solidifying the Iran–Syria alliance. Syria and Iran signed a fresh military cooperation agreement on 27 August at a meeting between their defence ministers at which they reiterated the need for Iranian forces to stay in Syria.

What makes the Iranian presence in Syria hard for the US to swallow is that, unlike the Russian presence, it threatens Israel’s self-defined security interests. But Washington must understand that Iran’s commitment to the Assad regime is qualitatively different from Russia’s. A couple of years ago, before the military tide turned decisively in favour of the regime, Moscow seemed willing to countenance Assad’s removal in order to forge a settlement between the regime and opposition forces.

Iran’s alliance with the House of Assad, on the other hand, is much more firm. It goes back to 1980 when Syria under Hafez al-Assad was the only Arab country that stood by Iran when Saddam Hussein, fearing the effect of the Iranian revolution on Iraq’s Shia majority, launched a bloody war against Iran that was bankrolled by Saudi Arabia and the Gulf sheikhdoms to the tune of US$20 billion. It lasted eight years and left a million Iranians dead.

More importantly, several realpolitik calculations determined Iran’s stance once the Assad regime was challenged—including the support extended by Iran’s nemesis Saudi Arabia and its Gulf allies to insurgent factions and the initial US determination to expedite regime change in Damascus because of Assad’s close relations with Iran. The increasingly Sunni Islamist and virulently anti-Shia colour of the Syrian insurgency further influenced Iranian decision-making.

Now that the Assad regime has regained control of most of Syria, Iran wants to reap the rewards for its assistance during the regime’s worst times. Much of the regime’s success can be attributed to the military training and advice provided by Iran’s Islamic Revolutionary Guard Corps and the fighting capability of battle-hardened Hezbollah forces from Lebanon trained by the IRGC. Hundreds of Iranians, including senior members of the IRGC, have been killed fighting on behalf of the Assad regime.

Iran is also keen to profit financially from the reconstruction program that’s bound to follow the end of the civil war. And it isn’t willing to give up its strategic foothold in Syria, which would complement its political presence in Iraq and, through its Hezbollah proxy, in Lebanon, and also provide it direct geographical access to its Lebanese ally.

This strategy isn’t so much about creating a ‘Shia Crescent’ in the heart of the Arab world. It’s more about Tehran’s desire to help stabilise friendly regimes in Iraq, Syria and Lebanon to counter Saudi moves, which are part of the cold war raging between the two principal powers of the Persian Gulf to deny Iran entry into the Arab world. Therefore, to expect Iran to eliminate or even reduce its presence in Syria is a pipe dream. Despite speculation to the contrary, Assad is more than comfortable with the Iranian military presence in the country—both because it serves his immediate purpose of regime maintenance and because he doesn’t want to become overly dependent on Russia, which might withdraw its support to preserve its other more pressing interests.

Under these circumstances, America’s efforts to persuade Russia to induce Iran to leave Syria appear futile. To avoid getting embroiled in a Middle Eastern conflagration, Russia has assured Israel that it will keep Iranian forces at least 85 kilometres from the Israeli border (except for in and around Damascus, where there’s a formidable Iranian presence which Tehran considers non-negotiable). So far, it has succeeded in doing so. But Russia is in no position to force Iran to leave Syria or even reduce its military and political presence. Washington will have learn to live with the fact that Iranian forces will be in Syria for a long time.