Michael Bell has been four times Canadian ambassador in the Middle East. He has been director general for Eastern Europe and director of Middle East relations in the Department of Foreign Affairs.

When the Islamic State's heyday is over, possibly sooner rather than later, like-minded Western countries, led by the United States and including Canada, will be faced with a much more challenging dilemma: What, if anything, can be done about the regime in Damascus? I believe there is no realistic alternative other than accommodating Bashar al-Assad's continued rule, however gut-wrenching this may be.

Islamic State is under growing pressure both in Syria and Iraq. While by no means defeated, IS is experiencing significant losses from which it will not recover. Major battlefield successes for these fanatics are past. Its forces are now thin after being subjected to punishing allied air attacks: the group is accelerating the move to urban areas to protect itself; in turn leading to dramatic increases in civilian casualties inflicted by these attacks.

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In northern Syria, the Kurdish dominated Syrian Democratic Forces are gaining ascendency against the Islamic State. They crossed the Euphrates River after seizing the Tishreen dam last month and are now advancing toward the ISIS held town of Manbij.

The Assad regime has within the last week cut off the rebels in northern Aleppo from the rest of the insurgency. The city itself is threatened. Regime forces are also progressing in the south near the Jordanian border, where the mainstream opposition collapsed last week in the city of Sheik Miskin after 33 days of Russian air strikes.

Air strikes are but one element bolstering Mr. Assad's new assertiveness, accompanied by massive shipments of Russian tanks and other material. Just as important has been the influx of Russian and Iranian advisers, Iranian controlled militias and continuing Hezbollah commitment.

To be sure there have been – and will continue to be – setbacks for the regime. Syria is unlikely to ever be reconstituted as it was. But any assessment that the Russians will lessen their commitment, or that the Iranians will back off, because their own economies are under stress, misreads the situation. Moscow is determined to support its only Arab ally.

To characterize Russian President Vladimir Putin as the interfering new boy is to misunderstand the state of affairs. The Syrian-Russian alliance is of historic proportion. Russian strategy demands it remain involved: Just as important is the psychological dimension – the Russian people's quest for status and respect both in the region and globally. Mr. Putin will not be ignored.

Repeated Western efforts are being made to get the parties around the table. For the United States and its Western allies, there seems to be no alternative but to keep at the diplomatic route, however remote the prospect of success. To abandon the field is viewed as the council of despair.

But for Mr. Assad and his allies there will be no accommodation. He would have to be abandoned by his allies and tottering badly on his left foot before he would entertain any meaningful compromise, only to undermine it at the first opportunity. Syrians have no pluralistic tradition, nor have their neighbours, as the collapse of the state system following the Arab Spring makes clear.

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Syrian tactics are brutal and nasty, without compassion. If this is what the regime feels it needs to survive, there will be no hesitation with barrel bombs or whatever else. One should not forget however that the Syrian state remains the country's largest employer. Damascus is the primary provider of food, fuel, health care and education. It remains the protector of minorities: Christian, Druze, Alawite, Ismaili and Shia. Mr. Assad's turf, if they can get there, remains the option of choice for the internally displaced.

Unhappily authoritarianism, most often brutal, is endemic to the Middle East. We Canadians find it near impossible to recognize this reality. If however we could accept a few basic if painful truths, we might just start to get somewhere.