The 13-year civil war in Syria has roared back into prominence as insurgents seized Aleppo in a shock offensive marking a major threat to president Bashar al-Assad’s brutal regime.The push – which saw insurgents seize the country’s second-largest city – is among the strongest in years,

Syrian rebels have swept through parts of the country at lightning pace, taking control of the the second-largest city, Aleppo. But who are they and what are their aims?

A surprise offensive by rebel forces opposed to Syrian President Bashar al-Assad's regime has led to a new round of fighting in a largely static civil war.