United Nations assessment reveals extensive destruction in western Mosul

Army First Lieutenant Nayef al-Zubaidi, for his part, told Anadolu Agency that Iraqi security forces had received numerous appeals from civilian residents of IS-held areas to refrain from targeting homes being used by the terrorist group to carry out attacks.

Lise Grande, U.N. Iraq humanitarian coordinator, says: "The level of damage in western Mosul is already far greater than in the east, even before the battle to retake the Old City begins".

The UN expects many more to flee, Grande said. ISIS is using vehicle-borne bombs, direct and indirect fire, and human shields to slow that advance, he added. They've intensified their efforts to bring civilians into harm's way.

They also announce that the targeted location was in fact a "fighting position" for Syrian Democratic Forces, who are allies in the US mission to fight the Islamic State. "This is something that is a despicable and cowardly tactic", he said.

About the USA -led coalition's coordination with Iraqi forces in Mosul operations, al-Alusi said: "Poor weather conditions in the region have reduced airstrikes of the global coalition's warplanes on Daesh-linked sites in western Mosul".

The combination of "explosives, booby traps, snipers, the use of civilian shields", he emphasized, "just makes it very slow and hard going".

Colonel Dorrian said the fight in Western Mosul had been tough but said IS fighters had no escape.

The US announced the invasion of Raqqa late previous year, starting an effort to surround the city which is still going at a slow rate.

The spokesman said "incremental" to describe the slow, careful progress is simply "an accurate discussion of what's happening". So we knew that it was going to be very hard.

There is only a "shrinking cordon" in Mosul where ISIS can operate, Dorrian said.