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,

In a swift and unexpected offensive, Hayat Tahrir al-Sham (HTS) captured Aleppo, Syria’s second-largest city, with minimal resistance from government forces, NPR reports. The Islamist group, formerly linked to al-Qaeda, has transformed into a national entity, focusing on governance and strategic alliances in Syria’s civil war.