Syrian pro-regime forces backed by Russian airstrikes have expanded their ground offensive to the strategic city of Aleppo, one of the clearest signs yet of how Russia’s recent military intervention has emboldened President Bashar al-Assad and his loyalists.

In the bitterly fought multi-sided war, Aleppo is among the most coveted prizes. Losing partial control of the city, which was once Syria’s largest and its commercial capital, was an embarrassment to the regime. But with the backing of Russian warplanes, Iranian forces and the Lebanese militia Hezbollah, Mr. Assad’s forces could now be in position to regain large parts of the city and the surrounding countryside.

“I suspect Assad always wanted to take back Aleppo because it is such an important city and retaking it has such strategic and symbolic importance,” said Emile Hokayem, a Middle East analyst at the International Institute for Strategic Studies, a London-based military and security think tank. “And it would deny the rebels a foothold in any major city.” […]