Masrour Barzani, head of the Kurdistan Regional Government's Security Council, said that even if Islamic State is driven out of its main stronghold Mosul, that will not be enough to eliminate the group, and its radical ideology will survive.
"The fight against ISIS is going to be a long fight," Barzani told Reuters in an interview. "Not only militarily but also economically, ideologically."
Barzani said Iraqi forces have made quick progress clearing out Islamic State fighters from eastern Mosul after Kurdish peshmerga units broke through its first lines of defense.
"As they are getting more desperate, expectations are that they might fight more fiercely as you close in," said Barzani.
So far in the three-week operation, Islamic State has deployed drones strapped with explosives, long-range artillery shells filled with chlorine and mustard gas and highly effective snipers, said Barzani. Kurdish forces have destroyed more than 50 car bombs.
And he cautioned that western Mosul will be a more complex campaign, with a vast number of narrow streets that can't accommodate large military vehicles and an enemy that will fight to the death to defend the capital of its so-called caliphate.
"There are many different IEDs (improvised explosive devices) that they put in different places, come up with different tactics. Many that are used like networks," Barzani said.
"So in one house they are putting one IED and trying to hide it. And once it explodes then the entire neighborhood explodes."