The Syrian military said on Saturday that dozens of its troops had been killed during a militant attack in northwestern Syria and that militants had managed to enter large parts of Aleppo city, forcing the army to redeploy. The Syrian military statement was the first public acknowledgement by the army that insurgents led by the Islamist Hayat Tahrir Al-Sham had entered the government-held city of Aleppo in a surprise attack that began earlier this week. “The large numbers of terrorists and the multiplicity of battlefronts prompted our armed forces to carry out a redeployment operation aimed at strengthening the defense lines in order to absorb the attack, preserve the lives of civilians and soldiers, and prepare for a counterattack,” the army said. The insurgent attack marks the most significant challenge in years to President Bashar Assad, jolting the frontlines of the Syrian civil war that have largely been frozen since 2020. The Syrian military statement said that the insurgents had not been able to establish fixed positions in Aleppo city due to the army’s continued bombardment of their positions. Two Syrian military sources said earlier that Russian and Syrian warplanes targeted insurgents in an Aleppo suburb on Saturday. Russia deployed its air force to Syria in 2015 to aid Assad in the Syrian civil war, which began in 2011. The insurgent force began its surprise offensive earlier this week, sweeping through government-held towns and reaching Aleppo nearly a decade after government forces backed by Russia and Iran drove militants from the city. Speaking on Friday, Kremlin spokesman Dmitry Peskov said Moscow regarded the militant attack as a violation of Syria’s sovereignty. “We are in favor of the Syrian authorities bringing order to the area and restoring constitutional order as soon as possible,” he said.