How ISIS lost control of its last major stronghold in the Middle East

Rodi Said/Reuters

Fighters from the Kurdish-dominated Syrian Democratic Forces celebrating their victory over the Islamic State in Raqqa, Syria on Tuesday

After months of fighting, the US-backed Syrian Democratic Forces (SDF) have conquered Raqqa, the capital of the Islamic State's so-called caliphate and its last major stronghold in the Middle East.

But the victory by no means indicates that ISIS is defeated, and enormous ethnic challenges still lie ahead for the embattled country.

Here's how the Raqqa campaign was won, and what lies on the horizon for Syria: