As the economic hub of Syria, Aleppo has been roughly divided between rebel control in the east and government control in the west since mid-2012.
The Syrian government forces have surrounded the rebel-controlled part of the city since July 17th. The UN estimates about 300,000 civilians are trapped without access to food or medical aid. On July 28th, Russia announced that three humanitarian corridors were to be opened "to aid civilians held hostage by terrorists and for fighters wishing to lay down their arms".
Another corridor was being opened to the north of the city for rebels to flee. On August 1st, Russia said seven such humanitarian corridors had been opened. Syrian government forces delivered food and fuel to neighborhoods within their control on Monday. They used an alternative road as rebels had cut off the main supply route in their latest assault in southwestern parts of the city.