Eastern Syria (CNN) Fighters from the US-backed Syrian Democratic Forces (SDF) have launched an assault to oust ISIS from its last remaining enclave in Syria, the final remnant of the jihadist group's so-called "caliphate."

At its peak, ISIS held large swaths of Iraq and Syria -- an expanse about the size of Portugal.

Its territory has now shrunk to a tiny pocket in Syria's eastern Deir Ezzor province, with militants holed up in the village of Baghouz Al-Fawqani, near the Iraqi border.

After pausing more than a week to allow tens of thousands of civilians to flee the town, the SDF on Saturday renewed its push to wrest the last 4 square kilometers (1.5 square miles) from the militants.

"The SDF has launched its final battle to eliminate the terrorist ISIS organization in Al-Baghouz village; the last ISIS stronghold," the SDF said in a statement.

Civilians who fled fighting in Baghouz Al-Fawqani board trucks Saturday after being screened by the Syrian Democratic Forces.