Syrian armed opposition forces have entered Aleppo just three days into their surprise offensive, marking the first time they have set foot in the country’s second largest city since government forces recaptured the city in 2016.

A rebel commander said a fall in Iran-backed manpower created an opening this week's assault. Iran's ally Hezbollah has suffered big losses to Israel.

BEIRUT—Syria’s antigovernment rebels claimed a stunning advance into Aleppo, a major symbolic and strategic prize, in a setback for the government in Damascus and its allies Russia and Iran.Islamist-led insurgents poured into Aleppo two days after launching a stunning strike from the country’s rebel-held northwest and eight years after the city fell to forces loyal to the government of Bashar al-Assad at the end of a long siege.