Pitched against the mix of Islamists and non-ideological rebels in the rubble is the strongest force that Bashar al-Assad has been able to call on at any point during the four-and-a-half-year war. An Iranian military brigade is stationed around 20km south, along with hundreds of Hezbollah fighters, Shia militias from Iraq and the Syrian Army.
A senior US official on Friday said the Pentagon estimated the Iranian strength at 2,000 officers and soldiers – Tehran’s largest contribution to a battle and a signal that it is no longer shy to acknowledge the fact that its troops are actively defending the regime.
Straight from a grinding battle in the mountains near Damascus, Lebanon’s Hezbollah has also travelled to Aleppo en masse.
Rebels inside Aleppo say they have the weapons and the stamina to keep their enemies from seizing the eastern half of the city they have controlled since July 2012. They say that large numbers of anti-tank missiles supplied by their allies – Turkey, Saudi Arabia, Qatar and the US – have reached them in recent days and warn that they have had three years to prepare their defenses.
However, rebel numbers have been stretched by a three-pronged advance on the city; the attack from the south, a similar push from Idlib province towards western Aleppo, where opposition groups had been trying to besiege the regime-held area, and also from a resurgent Islamic State, which is now within striking distance of the city’s northern limits.
The few remaining residents of eastern Aleppo, most of whom lived in areas that had been repeatedly barrel-bombed by the Syrian air force, were now fleeing. Civilians immediately started leaving their houses in waves and fled to the neighboring villages.
Usama Abuzaid, a senior adviser to the Free Syria Army, said: “In the last couple of days the attacks increased everywhere in the countryside, even in the areas where ISIS is trying to advance.
“Aleppo is very important for everyone. For us, it is our supply line to Turkey for food and weapons. Also, it has a revolutionary value for us. It holds our main FSA headquarters, and that’s the reason the Russians are advancing.