Islamic State has lost most of the territory it has held in Iraq since 2014, an Iraqi military spokesman said on Tuesday.

At the height of its power, the militant group controlled about 40 percent of Iraq, joint operations command spokesman Brigadier General Yahya Rasool told a news conference.

That area has been whittled down to about 6.8 percent of Iraqi territory after extensive military operations, which are still going on in the city of Mosul, he said.

Islamic State militants still control the towns of Qaim, Tal Afar and Hawija in Iraq, as well as Raqqa, their de-facto capital in Syria.

The coalition battling Islamic State is made up of tens of thousands of members of the Iraqi security forces, led by the army, and thousands of Shi'ite volunteers, many from militia groups, commonly referred to as the Popular Mobilization Units (PMU).

The United States and other Western countries have assisted with air support, intelligence and equipment, General Rasool said.

The battle for Mosul, one of Iraq's largest cities, began last October and the outcome will likely determine whether Iraq's various sects can work together to keep the country from fracturing.

The eastern half of the city is now completely under the control of Iraqi security forces, Rasool said. But the push against Islamic State in Western Mosul is bogged down with Iraqi security forces fighting in a warren of small streets in the old part of the city.

Also instrumental in the fight against the Islamic State has been the decimation of the group's operational cells, "which spread fear across a swath of territory that the jihadists do not actually occupy, that will be key to finally crushing IS here," reported Scott Peterson last year for The Christian Science Monitor:

The fact that the Iraqi government is making gains against IS militants illustrates how its intelligence apparatus has improved against IS, says Hisham al-Hashimi, a security analyst in Baghdad who advises the government on Sunni militant groups. “Their ability and capability became stronger and more developed” since the jihadists shocked Iraqi security and intelligence forces with their lightning offensive in June 2104, says Mr. Hashimi. “They have broken the back of these IS supporters in the north, south, and east of Baghdad.”

The federal police said in a statement on Tuesday they have been reinforcing their positions in Western Mosul in preparation for a push on the al-Nuri Mosque where Islamic State leader Abu Bakr al-Baghdadi declared a caliphate in 2014.

Islamic State has used hundreds of car bombs along with drones rigged with explosives in Mosul. Its fighters have pulled civilians into the conflict by placing snipers in residential areas, using civilians as human shields and executing those who try to escape, coalition spokesman Col. John Dorrian said at the news conference.

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

"Do not lose sight of the fact that even though the fighting is going to be very hard, this enemy is completely surrounded," Dorrian said. "They aren't going anywhere."