Anti-government rebels in northern Syria have launched a sudden offensive in an effort to capitalize on Israel’s efforts to weaken Iran’s regional proxies.

Syria’s antigovernment forces claimed a stunning advance into Aleppo, in a setback for the government in Damascus and its allies Russia and Iran.

The surprise attack, led by the Islamist group Hayat Tahrir al-Sham, was the boldest rebel assault for years in the civil war that has been frozen.