SCOTT SIMON, BYLINE: This is WEEKEND EDITION from NPR News. Rachel Martin has become a mother once more on this Father's Day morning. I'm Scott Simon filling in for her. The news from Iraq today - Shiite Muslim militias are helping to stop an advanced by the Sunni extremists group known as the Islamic State of Syria and Iraq. The U.S. is sending warships to the Persian Gulf. President Obama is considering a range of options, though, he has ruled out sending U.S. troops back into Iraq. Of course, U.S. forces subdued Sunni militants in the Anbar province in Baghdad starting in 2007 during a period known as the surge. Col. Peter Mansoor was there. He was an aide to Gen. David Petraeus. He is now retired and teaching military history at the Ohio State University. Col. Mansoor joins us now. Colonel, thanks so much for being with us.

COLONEL PETER MANSOOR: Oh, my pleasure. Thanks for having me on.

SIMON: President Obama said the Iraqis have to have a political plan in place before the U.S. considers military action. But does the situation on the ground permit that kind of time?

MANSOOR: Yes, it does. The - I think ICL offensive has run its course. When they get to Baghdad, they're entering a city of nearly 6 million people, lots of Shiite militias. The Iraqi security forces in the area are much more competent. And they would have a very, very difficult time making inroads into that city. I also commanded a brigade of 3,500 soldiers in 2003-2004 in Baghdad. And I can tell you that city swallows up entire armies. So we have plenty of time to get the politics right. I think President Obama, with his comments on Friday, is on the right track.

SIMON: What are the - if I might put it this way- pros and cons of airstrikes to inflict damage on the insurgency?

MANSOOR: Well, a lot of cons and very little pros. So first, in the pro-column, if you can catch an ICL column on a road in their pickup trucks heading to Baghdad, you could destroy it. And that would blunt any offensive. But let's talk about the cons because they are many and legion. ICL has blended into the civilian population in these cities they've taken. And trying to hit them there would invariably lead to a lot of civilian death. And then a lot of anti-American feeling by the citizens on the ground. Also, we would be supporting Nouri al-Malaki and his government in what is shaping up to be a civil war - Sunni versus Shia. And that's not the way you win this conflict.

The way the surge worked is we created deals with the Sunni tribes and so forth that became every one against al-Qaida. And that's what we need now - a unity government that is legitimate, represents all sects and ethnicities in Iraq. And then it can become every one against ICL rather than Sunni versus Shia.

SIMON: Col. Mansoor, what do you make at the performance of the Iraqi army? Melting away isn't what they were trained to do, I assume.

MANSOOR: No. But in the interim since our departure, Nouri al-Malaki has replaced a lot of the competent commanders with political cronies in order to ensure that the army remained loyal to him. He coup-proofed it, but then he also made sure that it couldn't fight effectively. And the soldiers aren't going to fight for Nouri al-Malaki. They've got to fight for something bigger than that. They've got to fight for Iraq. And right now, in many of their estimations, Iraq isn't worth fighting for.

SIMON: Col. Mansoor, let me ask you this in the half a minute we have left. You commanded soldiers. You lost some friends, I'm sure. What is the responsibility that the U.S. now has in Iraq?

MANSOOR: You know, it's deeply frustrating for those of us who have fought there to see the recent turn of events. But, you know, Iraq is its own nation. And the United States doesn't really have a moral responsibility to go back in with military force. I think we could do so if it's in our national interest, and I think it is. But only if it's an Iraq worth supporting.

SIMON: Retired U.S. Army Colonel, Peter Mansoor. Thanks very much for being with us, Colonel.

MANSOOR: Thank you for having me on. Transcript provided by NPR, Copyright NPR.