Updated

Iraqi forces have started to push into northern areas of Mosul in a new front in their battle against Islamic State fighters.

The forces are fighting their way into the northern part of western Mosul, a region where ISIS fighters are known to be holding onto a group of neighborhoods. Iraqi army, federal police and elite rapid response units are all engaged in the new effort.

Fighting for the western part of Mosul has been slower and deadlier than initially anticipated. A U.S. official said that 774 security forces have been killed in more than six months of fighting. At least 4,600 others have been injured.

The Mosul neighborhoods under ISIS control are still home to hundreds of thousands of people.

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For those battling ISIS, it will be a choice of “victory or martyrdom,” the spokesman for the Iraqi ministry of defense stated.

Iraqi federal police are currently a few hundred meters away from the al-Nuri mosque, the same symbolic location where ISIS leader Abu Bakr al-Baghdadi made a public appearance in 2014. There, al-Baghdadi designated the terror group’s caliphate after they took over almost a third of Iraq.

But getting to the mosque has proven to be troublesome for security forces. Difficult fighting is still anticipated due to the narrow streets surrounding the site, coalition officials said.

Iraqi forces seem to be circling the old city before proceeding with their operation to clear it.

ISIS took Mosul in 2014 and an operation to take it back has been underway since October 2016. In January, Iraqi forces announced that the city’s eastern half had been “liberated.”

The Associated Press contributed to this report.