MOSUL/BAGHDAD: Iraqi special forces battling Daesh (ISIS) reached the eastern bank of the Tigris River in Mosul Sunday for the first time in a three-month, U.S-backed offensive to capture the city from the militants, who still control its entire western half. Units of Iraq’s elite Counter Terrorism Service have fought their way to the eastern bank of the Tigris, spokesman Sabah al-Numan said.

It was the first time Iraqi forces in the city itself have reached the river, which bisects Mosul, since the offensive to drive out Daesh was launched in October.

Iraqi forces already control the Tigris to Mosul’s south.

The CTS has spearheaded advances inside Mosul and is part of a 100,000-strong force backed by U.S. air power of Iraqi troops, Kurdish fighters and Shiite militias fighting the militants.

Several areas around the city, Iraq’s second-largest, were swiftly reconquered, but the elite forces that pushed into the streets of Mosul itself have faced stiffer-than-expected resistance.

After a period of stuttering advances in Mosul, Iraqi forces have gained momentum in a new push since around the start of the year.

Having eyes on the river should further complicate Daesh’s already reduced ability to resupply the eastern front with fighters and weapons from the west bank, which it still firmly controls.

CTS forces also clashed with Daesh fighters near a historic site in eastern Mosul, an officer said, in a bid to drive them out of more neighborhoods. “This morning CTS troops advanced in two directions toward the Baladiyat and Sukkar districts,” Lt. Gen. Abdel-Wahab al-Saadi said.

“During the advance, Daesh tried to confront us from the historic hill,” he said, apparently referring to a hill located near the ruins of the ancient Assyrian city of Ninevah, east of the river and inside Mosul.

Saadi said that Iraqi forces and warplanes from the U.S.-led coalition “dealt with” Daesh fighters positioned on the hill, and dozens were killed.

Commanders had predicted when the operation was launched that the eastern side of the city would be easier to retake.

But the militants, estimated at around 5,000 to 7,000 before the start of the offensive, fought back with sniper fire, booby traps and a seemingly endless supply of suicide car bombs.

The continued presence in the city of hundreds of thousands of civilians – either forced to stay by Daesh or reluctant to leave their homes for crowded and cold displacement camps – has also impeded the federal advance.

Baghdad and partnering aid organizations had predicted an exodus of civilians in the first weeks of the operation, but the flux of fleeing Mosul residents was more limited than expected.

The western bank of the city is slightly smaller than the east but more densely populated and includes neighborhoods that are seen as bastions of support for Daesh.

Elsewhere, Iraq’s Kurdish regional government said in a statement Sunday that Kurdish and coalition forces killed a Daesh figure in a joint operation near the city of Kirkuk on Jan. 5. The operation took place in Hawijah, it said. Daesh have a smaller presence in the area.