US-backed fighters are moving slowly into ISIS extremist group’s final pocket in eastern Syria to avoid losses in the face of sniper fire and landmines, a commander said on Monday.

Warplanes flew above Baghouz, a cluster of houses on the banks of the Euphrates at the Iraqi border where ISIS fighters still hold out, and smoke rose from the area along with the sound of intermittent clashes.

The defeat of ISIS at Baghouz will mark a milestone in the campaign against the extremist group, ending its control of populated territory in the area straddling Iraq and Syria where it suddenly expanded in 2014 and declared a caliphate.

However, it has already shown it will continue to mount a potent security threat, with a string of insurgent attacks in both countries.

Pro-Syrian government forces hold the opposite bank of the Euphrates across from Baghouz and Iraqi militias are stationed at the border, cutting off any easy escape route for the extremists.

The Syrian Democratic Forces (SDF) has made “modest advances” since resuming its assault late on Sunday, killing and wounding many extremist fighters said Adnan Afrin, a senior commander in the US-backed militia.

The SDF pressed on with operations on Monday along with coalition airstrikes, but Afrin said advances were slow because the SDF wanted to complete the campaign with minimal losses.

ISIS fighters attempted four suicide attacks but the SDF captured an arms dump, said militia spokesman Mustafa Bali. One SDF fighter was killed and four wounded.

The SDF has held off from a full assault for most of the past few weeks as many thousands of people poured from the enclave, including surrendering fighters, ISIS supporters, other civilians and some of the group’s captives.

By Sunday evening, no more people had come out, prompting the SDF to start its attack.

Reuters