The offensive marks the most significant fighting in Syria's civil war in recent years Read more
now playing
Syrian troops withdraw from Aleppo
The offensive marks the most significant fighting in Syria's civil war in recent years
Syrian rebels seize the second largest city, Aleppo
The assault on Aleppo is the biggest challenge to the Assad regime in years
Syria: Dozens of soldiers killed as rebels advance
Russia conducts strikes in support of the Syrian army
