In a shocking offensive, Turkey-backed Syrian rebels led by Hayat Tahrir al-Sham on Friday invaded Aleppo and claimed control of "half" the territory of the city, revealed the Syrian Observatory for Human Rights (SOHR).
Around 200 people have been killed in the violence. Syria has shut the Aleppo airport and cancelled all flights on Saturday.
The Assad regime claimed it was fighting back and had inflicted heavy losses on the insurgents in Aleppo and Idlib provinces.
Aleppo was recaptured by the Bashar al-Assad regime in 2016 and the latest violence has once again brought the world's attention to the country that has been struggling with civil war for the past 13 years.
Aleppo, the second largest city in the country, is around 350 km away from Damascus. The city was first captured by the rebels in 2012, when they claimed control of the eastern parts of Aleppo. It was recaptured by Assad forces with the support of Russia and Iran four years later.
The Assad regime controls 70 per cent of the Syrian territory currently while the remaining is occupied by rebels and the US troops. Turkey also controls parts of northern areas of Syria as it considers Kurdish militia in the region as allies of Kurdish separatists within its territory.
Israeli Prime Minister Benjamin Netanyahu held a special security meeting to discuss the developments in the neighbouring Syria amid ceasefire with Iran-backed Hezbollah. Israel is reportedly worried about strategic weapons in the possession of the Assad regime falling into the hands of militants.
Iran, which backs the Assad regime, stated that it stands by Syria in combating "terrorism". Iran Foreign Minister Abbas Araghchi called the rebel resurgence a part of "the US-Zionist scheme".
Russia, which is also allied with Assad, promised to extend military aid to thwart the rebels.
Jaish al-Izza rebel brigade commander Mustafa Abdul Jaber said they could easily invade Aleppo as the city was low on manpower due to losses suffered by Iranian proxies amid Israel's war with Hezbollah.