The United States has tried to counteract this by persuading rebels to reject jihadists, in part by promising support for the opposition and by targeting jihadist militants. But the American approach has drawn the Syrian factions closer together, because rebels like those in Aleppo need urgent support on the ground and only extremist groups are available to provide it.

Removing Alternative Leaders

The endurance of non-jihadist rebel groups poses an even greater threat to the Syrian government than the jihadists because they challenge the Syrian government’s legitimacy.

That legitimacy has been weakened by years of killing civilians, and by the government’s strategy of fostering sectarianism, which leaves it with little support among the country’s majority Sunni population. As long as non-jihadist Sunni Arab rebels are on the battlefield, they can credibly claim to better represent Syrians. This leaves the Syrian leadership, which is dominated by the Alawite religious minority, vulnerable to any peace deal or military intervention that would install a rebel government in its place.

By forcing the rebels to unite with the jihadists, Syria’s government aims to deprive the world of any acceptable alternatives for leading the country.

Russia has a similar weakness. Syria, its last remaining ally in the Middle East, will remain that way only as long as it is led by the Alawite religious minority. Any democratic Syrian government would prominently feature Sunni Arabs, who are unlikely to look kindly on Russia after its role in the civil war.

Moscow has probably concluded it cannot force a military victory for the Syrian government. Its yearlong intervention has focused heavily on Aleppo, but pro-government ground forces are too weak to retake the divided city. Radicalizing the opposition, then, can ensure that there is no viable alternative to Syria’s current government.

Forcing a Seat at the Table

This also accomplishes a diplomatic goal for Russia: making itself crucial for any cease-fire or peace deal. Earlier in the war, it had less sway on the international stage — and perhaps with Damascus — because it played a smaller role than other countries that had intervened. Russia was unwilling to commit ground troops, making it secondary to Iran, which had sent many.