Civilians die, usually in untold numbers, in every war. Despite the Pentagon's assurances that U.S. forces would do as much as possible to avoid civilian casualties, it's estimated that somewhere between 4,000 and 10,000 Iraqi civilians died -- a startling number compared to the roughly 150 U.S. troops killed in the six-week invasion. Discussing the issue of civilian casualties in this war are historian Frederick W. Kagan, Marine Lt. Col. James Conway, New York Times correspondent Todd Purdum and Washington Post Pentagon correspondent Thomas Ricks. Their excerpts are drawn from their full FRONTLINE interviews.

Correspondent for The New York Times

There was a feeling among some of the British military that the U.S. tactics were possibly too dramatic and could lead to more civilian deaths -- true?

The British had had long experience in Northern Ireland dealing with the guerrilla resistance, and they were proud of how they handled that. They felt they knew what to do. They felt that they had done tactics during the battle and in the occupation afterwards that had a lighter hand, [which] worked better. They had the luxury, also, of working in Basra, which was one of the most sympathetic cities to the invasion, one of the cities that had been oppressed by Saddam -- a Shiite region that had suffered very much under Saddam's regime.

So it wasn't quite the same job the Americans had up in the Sunni Triangle and up in Baghdad, fighting a much more hostile population, much more resistance.

What about the apparent contradictions in U.S. policy on avoiding civilian casualties?

The American military made a great point of its intention to avoid civilian casualties whenever possible. But the truth is, it wasn't always possible. It was very difficult at times, partly because of the way the Iraqi regulars fought. Donald Rumsfeld reserved for himself the right to approve bombing targets in which certain numbers of civilians would be at risk. In fact, he approved more than 50 of those targets; every single one that came to him for consideration.

The truth is, war is brutal. War is terrible, and there's no getting away from it. The Americans didn't even try to count the Iraqi civilian casualties afterwards, and we may never know for sure how many there were. But it's one thing for the Pentagon to say it wanted to avoid civilian casualties, because I think it did. Could it avoid all civilian casualties? Not even close.

Why didn't we try to count civilian casualties or Iraqi casualties?

The Pentagon doesn't tend to count civilian casualties on the other side. I think there may be a lot of reasons for that -- one [is] because [of] the difficulty of getting a reliable number. I think it's also a kind of horrible, depressing number that no one wants to think about very much.

We'll never know for sure how many civilian casualties there were. After the war, The Associated Press did a tally, canvassing hospitals around the country. They came up with a figure of more than 3,200, but they acknowledged it was incomplete.

But do we know how many Iraqi soldiers died?

No, I don't think we really do know that.

What happened at the Diyala Bridge, and why the civilian casualties?

On their way from Kuwait, the Marines had crossed two of the world's great rivers, the Tigris and the Euphrates. During the battle of Baghdad, they found themselves stuck at a 60-meter tributary called the Diyala River. They were trying to cross it. There were reports that suicide bombers were headed for the bridge, and that had been a real threat before in the days before, this was true. So the American forces were very nervous. They were taking no chances. When the reports [came] that people were coming across the bridge, they wound up just more or less firing at any vehicle that tried to cross, even if it turned out to be civilians fleeing. A number of civilians were killed.

It was one of those tragic realities of what happens in war. We think of this war as one that had a lot of high-tech equipment, bombing from great heights. This was bloody, old-fashioned war, just like it was in the Middle Ages, and it was pretty grim.

Was one of the reasons that deaths occurred that the Marines were trigger-happy? That they had gone through so much in the days before that perhaps they were not taking time?

I don't think the Marines were trigger-happy. The truth was that they'd faced such intense resistance, often from civilians, that they just were unwilling to take risks. They were unwilling to die because they made a mistake, and the civilians, the Iraqi civilians, paid the price.

He led the U.S. Marines' 50,000 strong force in the 2003 invasion of Iraq.

There's been some criticism of the behavior of the Marines at the Diyala bridge in terms of civilian casualties.

Well, after the 3rd Battalion, 4th Marines crossed, the resistance was not all gone. … They had just fought to take a bridge. They were being counterattacked by enemy forces. Some of the civilian vehicles that wound up with the bullet holes in them contained enemy fighters in uniform with weapons, some of them did not. Again, we're terribly sorry about the loss of any civilian life where civilians are killed in a battlefield setting. I will guarantee you, it was not the intent of those Marines to kill civilians. [The Marines shot at certain civilian vehicles because] they felt threatened, [and] they were having a tough time distinguishing from an enemy that [is violating] the laws of land warfare by going to civilian clothes, putting his own people at risk. All of those things, I think, [were an] impact [on the behavior of the Marines], and in the end it's very unfortunate that civilians died.

Force protection and overwhelming force -- those two tactics have a complete logic in military terms, but would you accept that there are implications for any civilian population caught in the area when the Americans are using those tactics?

Well, there's always going to be impact on civilians in a battlefield environment. The best thing a civilian can do in a battlefield environment is go to ground and stay there. That's exactly what we told them to do in the information operations plan that was imposed -- leaflets were dropped.

You speak of overwhelming force. Those civilians who were killed were killed with rifle bullets or, in some cases, light machine guns. They weren't taken out with tank fire. They weren't struck with air [artillery], so I would offer that [the Marines were] using the minimum force needed at the time to defend themselves [against] enemy car bombers. The 3rd Infantry Division had lost a number of soldiers in this attack [from] car bombers. We had had Marines injured and a tank knocked out shortly before we crossed the bridge. So all of those things are in the minds of the Marines. There were warning shots fired that were not adhered to, and I think at that point the Marines … deemed that the vehicles represented a threat and took them under fire. In an ideal world we would have had MPs out there with cones and all the things that protect us at this base -- that's simply not possible in the heat of combat, as you're moving forward.

Are warning shots an appropriate technique in a civilian environment?

Our rules of engagement did not require warning shots, per se. There was nothing that said that if we thought that a force was threatened that we had to fire a warning shot to give them a chance to react; the warning shots I speak of are, [for example,] shots through the block of an engine, or shots that may show a tracer coming across the hood of a vehicle. Those were the things that I think the Marines were attempting to do: firing in front of vehicles, [stirring] up a dust cloud -- those types of things that would deter a civilian from driving and getting into the middle of a combat scenario.

Could [more thought] have been given beforehand to how roadblocks and checkpoints and perimeters are organized in civilian areas?

Had we perfect knowledge of what was going to happen, that the enemy was going to go to civilian clothes, attack us in taxi cabs and vehicles and try to blow us up, we might have found another way to do things. If you're asking me if I'm going to have a Marine go out and post a [stop] sign in the middle of a roadway when he's being shot at, I'm probably not going to do that. We terribly regret the civilian casualties, but those things happen in war. They're very regrettable, but I'm not going to expose Marines to arbitrary methods to try to preclude that situation. ...

Military Historian

What about civilian deaths in this war? How do tactics that were used in Iraq have an impact on that?

When you're talking about civilian casualties in war, it's very important to understand that there will always be civilian casualties in war. You can look at any specific instance when there was civilian casualties and point to, frequently, errors of judgment, or misperceptions, or confusion, or lots of things that cause them. You can dissect any given incident and say, "Well, they shouldn't have done this and they shouldn't have done that." But it's almost certain that, in any large war, that there are going to be incidents, and there are going to be civilian casualties.

The U.S military took extraordinary pains to avoid civilian casualties in a campaign in which an incredible amount of ordinance was dropped all across a country, including in extremely densely inhabited areas. Overall, America's success in avoiding large numbers of civilian casualties was astonishing.

The problem is we're living in a world where the expected rate of success is 100 percent. We count up from zero how many civilian casualties there are, and every one is unacceptable. Of course, in principle, that's true. In war, reality doesn't actually work that way.

My experience is that American soldiers and Marines are incredibly well-disciplined professionals, and are not readily rattled. I don't see any evidence that people were so rattled in this war that they were not capable of behaving professionally and using their proper judgment. I think when you get into situations like Nasiriya, where there's a very hard fight and the enemy's blending in with the civilian population, it's simply very hard to know all the time what the right thing is to do, and you get a lot of confusion.

But the notion that you have people who are on hair-triggers and shooting readily at things that they shouldn't be shooting at-- There may well have been instances of that, but I would be surprised to find that there were very many.

Pentagon correspondent for The Washington Post

There were certain points when there were a lot of civilian casualties. Can you address that?

We're holding the U.S. military to an extremely high standard, and I think it should be held to a high standard. I think most people in the military [that] I know would welcome that standard. On the other hand, a soldier inside a tank has a very limited view of the world. He literally can't see that much. So I always had a certain sympathy for the guys in the tank that shot up the Palestine Hotel and killed some journalists during the attack on Baghdad.

Journalists needed to reconsider how they thought about war. There's almost this attitude among some journalists that war is something that occurs in the field, and you can sit [in] the stands. It's not. Sure, it might be like a football stadium, but you have troops rumbling all over that stadium. You have [ammunition] being shot in every direction, missiles going off. There is no safe place in the stadium. I don't think it's reasonable to expect that there be a safe place in the stadium.

In my experience, the U.S. military really goes out of its way to minimize [the] shooting civilians and killing [of] civilians. It does happen. Ground forces, I think, tend to be more sensitive to it than air forces do. [An] air forces' attitude is, "Occasionally a bomb goes wrong. We're sorry. We don't like it. But it happens." Ground forces really tend to hold back, I think, on the use of force, partly because it is more personal, because it is somebody they can see.

One of the most striking stories of the war that I can remember is, Bill Branigin of the Washington Post witnessed an exchange in which an American officer was chewing out some of his troops for killing a family of Iraqis, because they hadn't fired soon enough. He was saying, "If you fired warning shots earlier, you wouldn't have had to shoot at their car. But you waited and waited. Then you had to shoot at their car, and it turned out to be an Iraqi family that was scared and trying to run away, and they zoomed right into your checkpoint." He said, "You just got this family killed because you guys didn't shoot fast enough."

It actually was a great example of why embedding reporters was a good thing. You don't get that sort of story sitting hundreds of miles away. You only get it if you're out there, listening to officers talk to troops, and seeing what's happening on the battlefield.