Russian President Vladimir Putin thinks Russian airstrikes in Syria have helped turn the war's tide, but the pace of the Syrian Army's advance has frustrated him, some sources say. If Aleppo falls, he could get the military and symbolic prize he has been craving.

More than four months of Russian airstrikes have stabilized the government of President Bashar Assad, the Kremlin's closest Middle Eastern ally, helping his forces find momentum on the battlefield.

But the names and strategic significance of the towns and villages they have recaptured have failed to electrify a Russian public more worried about falling living standards. Nor has the Syrian Army — backed by Russian air power — yet delivered a major victory that Russia can sell to the wider world as proof of its military might and growing Middle East clout.