MOSUL, Iraq -- President Trump has promised since his days on the campaign trail to wipe out the Islamic State of Iraq and Syria (ISIS), and while it’s still unclear how he’ll change U.S. policy to try and make good on that vow, the U.S.-backed fight with the Islamic extremists is about to take another significant turn on the ground.

CBS News correspondent Charlie D’Agata reports that in some neighborhoods of eastern Mosul, there is a sense that things are returning to normal. Iraqi forces have managed to liberate the eastern half of the city right up to the Tigris River, which divides it roughly in half.

ISIS still holds onto the western half, however, and D’Agata and his team were able to reach the centre of the city, where they saw some of the destruction left behind by the battle for Mosul thus far; it’s a grim landscape of flattened buildings, craters and debris left by gunfights that took place in relatively close quarters.

While the vast majority of the ISIS militants who held eastern Mosul for more than two years are now gone, even in the liberated half of the city Iraqi forces will still have to go house to house to root out any who may have melted into the community, and could still pose a threat as potential sleeper cells.

As D’Agata reports, there have already been examples of car bombs hidden in east Mosul garages that spring into action and attack Iraqi forces as they advance.

The last big battle for Iraq’s security forces facing ISIS will be wresting western Mosul back from the militants.

Iraqi commanders and residents say many of the extremists appeared to leave those areas in recent weeks as government forces advanced, likely heading to fortify ISIS’ defenses in the west.

The western half of the city has the oldest neighborhoods, with some of the narrowest streets -- some of them not even wide enough for vehicles to pass -- so much of the fighting will have to be done on foot.

U.S. Army Maj. Gen. Joseph Martin, who commands coalition ground forces in Iraq, admitted in an interview with The Associated Press that it is a “complicated environment.”

“West Mosul will be as tough as east Mosul, and from our view even tougher,” he said.

D’Agata notes that U.S. and coalition forces have blown up most of the bridges leading across the Tigris into the western half of the city, which is going to complicate things further for Iraqi troops.

It is now the last real stronghold ISIS has in Iraq, and they won’t likely give it up without a serious fight.