Two rebel groups are leading the push. One is Hayat Tahrir al-Sham ( HTS ), which emerged from al-Qaeda’s Syrian affiliate. It cut ties with the jihadist group in 2017 and has since set up a provisional government in rebel-held Idlib province in north-west Syria. The other faction, the Syrian National Army ( SNA ), is a Turkish proxy.

Rebels in Syria took control of the Nayrab Military Airport in Aleppo, Al Jazeera reported, citing opposition officials on December 2.Footage from local news outlet Shaam Network shows abandoned military planes and a helicopter at the base.

Syria holds strategic importance for Moscow and Tehran, which have both bolstered Syrian President Bashar Assad's regime at critical moments.

In just a few days, a patchwork of rebel forces has seized control of a broad stretch of land in the west and northwest of Syria. But it’s unclear just how much support Syria’s weakened allies can provide.

Fighters from Hezbollah and Iraq’s Shiite militias have deployed to Syria to support government forces, but it’s unclear if they are capable of turning the tide.

Ukrainian soldiers paint a bleak picture of a battle they don't understand, and fear they will lose.

Russia is sending private mercenaries to Syria to reinforce its troops, possibly its so-called Africa Corps, the Ukrainian military intelligence agency (HUR) claimed on Dec. 3.