President Assad's stranglehold around Aleppo has tightened considerably in the last few days.

Backed by the might of Russian jets, including its newest SU-34 fighter bombers, and Iranian Quds Forces, Syrian government forces have successfully taken the key villages of Zahraa and Nubbol north of Aleppo, cutting the rebels main route from Turkey into the besieged city.

Russia says it's hit 900 targets in just three days.

But a lightning storming of Aleppo is unlikely since street to street fighting would cost the already battered Syrian Arab Army thousands of troops.

The damaged streets of Aleppo pictured in September 2015 Credit: Reuters

Instead, it's more likely the government forces will tighten their siege, which combined with continuing, punishing, aerial bombardments by the Russians, will compound the misery of those civilians still trapped inside the city.

Rebel forces have been locked in an exhausting battle for years in Aleppo with the frontline barely moving.

I visited the city in January 2014 and remember surveying the devastated city from the roof of the governor's office, taking care to keep my head down for fear of rebel snipers.

  • Dan Rivers surveys Aleppo from the roof of the governor's office in this report from January 2014. Watch it in full here.

Now Assad's troops can attempt to consolidate recent gains with further strikes further north and south of these newly linked up positions around Zahraa.

The battles haven't come without costs. Iran has just confirmed the death of an IRGC Brigadier General, Mohsen Qajardyan.

Syria doesn't like to discuss Iranian support in its prosecution of the war, but its elite Quds Force is an important presence on numerous frontlines.

With their continued support, it raises the grim prospect of starving out the rebels who are now surrounded on three sides.

It's why Turkey's Prime Minister is warning of another wave of perhaps up to 300,000 refugees heading out of Aleppo towards the border, amid a growing realisation that despite stalled talks in Geneva, the momentum seems to be with Russia, Iran and President Assad.

It's why many are watching to see what Turkey will do next - Russia suspects Turkey may be preparing for a ground incursion into northern Syria, to halt Kurdish advances.

After almost five years, suddenly there seems to be a rapid change in the dynamics of Syria's proxy war. Watch this space...