GEN. DAVID PETRAEUS:

No, I think — with respect, I think he said it could take months, I think. Understandably, he's giving a bit of the worst-case analysis.

It's already moving faster than most predicted. I have said that, look, the Islamic State fighters that are left in Mosul, maybe as many as 5,000 or 6,000, they realize that they are dead men walking. There's no question that the Iraqi security forces, with all of the enablers that we're providing them, are going to clear that city. That's not in question.

The only question is, how long do the Islamic State fighters really put up resistance? There are reports already of substantial numbers of deserters, many of whom have been executed, and of leaders trying to leave the city as well.

In fact, one of the big questions that is out there right now is, where is Baghdadi, the leader of the Islamic State? Is he trapped there with one of his explosives experts, or did he actually escape to the west and try to get back across the border to Syria?

But, again, no question that the Iraqi security forces will prevail. The bigger question is actually the battle after this. And I have made clear in writing a couple of months ago, for example, that the most complex human terrain in all of Iraq is to be found in Mosul and the province of which it is a capital, Nineveh, biblical Nineveh.

There are Sunni Arabs in the majority, but there are also pockets of Shia Arabs. There are Turkmen, Sunni as well as Shia. There are Kurds, and they come from several political parties that they're not always in agreement with each other. There are sizable numbers of Christians that were treated horribly under the Islamic State and want to get back to their areas. There are Yazidis. There are Shabak.

And all of these want to get back from whence they came, and they want to play a part in governance that follows. And all will want to be represented and want that government to be responsive to them and guarantee their minority rights, if they're not the Sunni Arabs, in addition to, of course, the Sunni Arab majority rule.

This is going to be very, very difficult. We did achieve it early on in 2003, when I was privileged to command there. But we had 28,000 great American soldiers. We had 254 helicopters. And I had the authority of being an occupying commander under the Geneva Convention, and didn't hesitate, frankly, to use that authority.

There's no equivalent power there at this point in time. So, this is going to take intense politics, intense negotiations and a lot of individuals undoubtedly demonstrating the full range of emotions along the way.