Syrian and Russian jets are stepping up strikes on opposition forces in northern Syria in retaliation for the sudden offensive that has cost the autocratic regime control of the country’s second largest city,

As things stand this morning, the Syrian army says that anti-government forces have now taken control of "large parts" of Aleppo. Meanwhile, the country's president is vowing to "defend [Syria's] stability and territorial integrity in the face of all terrorists and their backers".

The surprise attack, led by the Islamist group Hayat Tahrir al-Sham, was the boldest rebel assault for years in the civil war that has been frozen.