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

Over a few days, rebel fighters in northern Syria have launched incursions into several major cities with little resistance from government troops.

Rebel forces in Syria have seized control of most of the city Aleppo after launching a surprise offensive against government forces, a war monitor reported on Saturday as Russia says it deployed fighter jets against rebels in Syria.

The rapid advance on Aleppo came just four days into a surprise rebel offensive that is the most intense escalation in years in the country’s civil war.

The insurgent offensive, shocking for its speed, has posed the most serious challenge to President Bashar al-Assad in years.

Insurgents have breached the Syrian city of Aleppo, clashing with government forces, according to a Syria war monitor and fighters.

BEIRUT (Reuters) -Syrian rebels opposed to President Bashar al-Assad said on Friday they had reached the heart of the northern city of Aleppo, after a surprise sweep through government-held towns and nearly a decade after having been forced out of the city.

Thousands of Syrian insurgents have fanned out inside Syria’s largest city Aleppo a day after storming it with little resistance from government troops

Thousands of Syrian insurgents fanned out inside Syria's largest city Aleppo a day after storming it with little resistance from government troops.

Syria state media say government troops are battling insurgents inside the country’s largest city Aleppo for the first time since 2016