The timing is no coincidence. Three weeks away from the US presidential election, and with US-led coalition forces focused on retaking Mosul, Isil's last stronghold in Iraq, Vladimir Putin is seizing the opportunity to reach two goals at once: declare victory in Syria and highlight US incompetence.

The stakes are high in Mosul. The battle for the city is seen by the US administration as the litmus test for Obama’s foreign policy doctrine of solving conflicts from the sideline – aiding our partners on the ground rather than leading every fight as the world’s policeman.

But while his strategy stands a chance to succeed in Iraq, it has as good as failed in Syria and the fate of eastern Aleppo could undermine the legitimacy of the Obama Doctrine before it even had a chance to establish itself.