It is the clearest example yet of the impact Russian bombing is having in Syria.
Hezbollah and other fighters loyal to President Bashar al-Assad, backed by Russian air power, are advancing on Syria's largest city Aleppo.
The fall of Aleppo could be a significant setback for rebel forces. They have managed to hold on to much of the city since 2012, but could now find themselves completely surrounded.
The rebels say that without outside help, Aleppo will fall. Saudi Arabia, Bahrain and the UAE say they may send ground troops. But it is unclear when or how that would work.
On Inside Story, we ask whether a Gulf ground force could tip the balance.
And what does the fight for Aleppo mean for Syria?
Presenter: Sami Zeidan
Jamal Khashoggi - Editor-in-chief of the Al Arab news channel
James Denselow - Research associate at the Foreign Policy Centre
Mohammad Marandi - Professor of political science at the University of Tehran
Source: Al Jazeera