The Syrian army said on Saturday dozens of its soldiers had been killed in a major attack led by opposition fighters from the Hayat Tahrir al-Sham group who swept into the city of Aleppo, forcing the army to redeploy in the biggest challenge to President Bashar al-Assad in years.Russia’s defense ministry said its air force had carried out strikes on Syrian opposition fighters in support of the country’s army, Russian news agencies reported. The strikes followed what was the boldest opposition assault for years in a civil war where front lines had largely been frozen since 2020.Hayat Tahrir al-Sham, or HTS, once known as the al-Nusra Front, is designated a terrorist group by the US, Russia, Turkey and other states. Al-Assad is a close Moscow ally.For all the latest headlines follow our Google News channel online or via the app.A spokesperson for the US State Department said earlier that the United States was monitoring the situation.The war, which has killed hundreds of thousands of