BAGHDAD (AP) — Iraqi forces have made significant progress as they close in on the Islamic State-held town of Tal Afar, west of Mosul, the U.S.-led coalition said Monday.

U.S. Army Col. Ryan Dillon, a coalition spokesman, told The Associated Press that Iraqi forces have retaken some 250 square kilometers (95 square miles) from the extremist group, though they have not yet pushed into the town itself.

"As we get into the urban areas — as we saw in Mosul and Raqqa — that's where we'll see the pace slow down, that's where (IS) have placed their defenses," he said.

U.S.-backed Iraqi forces drove IS from Mosul last month after a grueling, nine-month campaign to retake the country's second largest city. U.S.-allied forces are currently battling IS in the Syrian city of Raqqa, the extremists' de facto capital.

The operation to retake Tal Afar was launched early Sunday. Dillon said most of the territory retaken was in the Kisik junction area to the east of the town.

Tal Afar, about 150 kilometers (93 miles) east of the Syrian border, is in one of the last pockets of IS-held territory in Iraq.

Some 49,000 people have fled the Tal Afar district since April, according to the United Nations, sparking concern the displaced will exacerbate the humanitarian crisis that erupted during the Mosul operation. Nearly a million people remain displaced by the campaign to retake Mosul.