Russian and Syrian warplanes targeted insurgents in an Aleppo city suburb on Saturday, two Syrian military sources said after the rebel fighters penetrated the heart of the city in Syria’s northwest in a surprise attack the previous day. The attack by the Islamist militant group Hayat Tahrir al-Sham marks the most significant challenge in years to President Bashar al-Assad, jolting the frontlines of the Syrian civil war that has largely been frozen since 2020. The Syrian Civil Defense, a rescue service operating in opposition-held parts of Syria, said in a post on X that the Syrian government and Russian aircraft carried out airstrikes on residential neighbourhoods, a gas station, and a school in rebel-held Idlib, killing four civilians and wounding six others. Russia, which deployed its air force to Syria in 2015 to support Assad in the war, has promised Damascus extra military aid to thwart the rebels, the two military sources said, adding this would start arriving in the next 72 hours. The insurgent force began its surprise offensive earlier this week, sweeping through …