LLast week, apparently catching the world by surprise, Hayat Tahrir al-Sham (HTS) rebels launched a surprise offensive against government-controlled positions in northwestern Syria. Within 72 hours, incredibly, they had expelled Assad’s troops from large swathes of Aleppo. HTS’s triumph restored a rebel presence to Aleppo for the first time in eight years and paved the way for the unfreezing of the Syrian Civil War. Predictably, Russian fighter jets – supporting their ally, Assad – responded by bombing rebel-held areas of Aleppo and Idlib. Iran-aligned Kataib Hezbollah and Fatemiyoun militias also joined the fight on the dictator’s behalf. Regardless of what...