Here is what you need to know.
The Syrian army and its allies have been trying to retake the eastern half of Aleppo city from rebels since December 2016.
The government’s offensive was halted in February, after the Syrian army and its allies managed to push rebels out of the Old City and encircle them in the eastern part of the city.
Since then, the Syrian army has been trying to break the siege by rebels in eastern Aleppo.
In the past few weeks, the Syrian army and its allies have been trying to retake the eastern half of Aleppo city from rebels.