Knock-Out Punch?

I certainly can't rule out that vile jihadis used chemical shells on Syrian civilians, but the accusation seems like a pretext to end the pretend ceasefire in Idlib after it has run its course in dividing and weakening the remaining rebel stronghold in that Syrian province:

The Russian Defence Ministry said on Sunday its warplanes had carried out air strikes against militants it held responsible for firing shells filled with chlorine gas at the city of Aleppo, Russian news agencies reported.

Perhaps this is a one-off. But maybe it signals what the Russians hope is the final offensive in the west.

Are the rebels capable of abandoning a civil war objective of holding territory and going down the escalation ladder to an insurgency?