The Syrian government says it's preparing to retake the city of Aleppo from rebel fighters.
It comes as the fragile ceasefire looks to be on the verge of collapse.
It's been a long, gruelling and violent fight.
In a video posted online, Syrian rebels are seen cutting through the countryside of Aleppo.
On the ground, rival rebel factions, government forces and Islamic state fighters are all locked in battle, vying for control.
But the fight for Syria's commercial hub is also being waged from the air.
Syrian government forces are being backed up by Russian military jets. They're staging a joint operation to wipe out rebels and take Aleppo city and province.
While in Damascus, the UN Envoy Staffan de Mistura is desperately trying to salvage the struggling ceasefire.
It came into effect in February but like those before it, it has been violated.
Neither the al-Qaida-linked al-Nusra front rebels nor the Islamic State are included in that ceasefire deal.
Their presence in Aleppo makes the area all the more volatile and the battle for it more brutal.