President Clinton said force is sometimes "the only answer" in a speech today at the Pentagon. If it does come to a military strike against Iraq, what weaponry will the U.S. use? Following a background report, Jim Lehrer talks to four retired military commanders about the possibilities.

The President's speech:

MARGARET WARNER: Joining us now four retired military commanders: General Merrill McPeak was Air Force chief of staff during the Persian Gulf War; Admiral Leighton Smith was the director of operations of U.S. forces in Europe during the Gulf War, coordinating NATO support for the U.S.-led coalition against Iraq. More recently, he commanded the NATO implementation force in Bosnia. General John Sheehan was in charge of Marine amphibious forces in the Gulf War. Most recently, he was commander in chief of the U.S. Atlantic Command. And General Bernard Trainor retired from the Marines before the Gulf War; he's now affiliated with Harvard University's Kennedy School and writes military analysis for the New York Times. General Trainor, can a military operation achieve the goals outlined by the president today?

LT. GENERAL BERNARD TRAINOR, U.S. Marine Corps (Ret.): The president has been very careful not to be too specific as to what those goals are. He speaks in generalities. And if you're looking to damage Saddam Hussein's capabilities, both his conventional capability and to the degree that we know about it, his unconventional capability, we have the capability, ourselves, of doing that. But as he has been careful to point out, this is not something that is going to solve the problem, and, if necessary, if Saddam Hussein continues to misbehave, the United States, representing the international community, is willing to repeat the operation.

So I think the signal to Saddam Hussein is he either conforms, or he is going to suffer mightily.

MARGARET WARNER: General McPeak, do you think a military operation can achieve the goals that the President outlined today, which were to--I think he put it to reduce--diminish the threat of Iraq's weapons of mass destruction and his ability to threaten his neighbors with those weapons?

GENERAL MERRILL McPEAK, U.S. Air Force (Ret.): Yes, Margaret. We're in a unique position here to define success. The President said that we want to seriously diminish the threat that Saddam Hussein poses to his neighbors.

He didn't say that we're going to take out 100 percent of the chemical, biological, nuclear capability. And it's good that he did not because that would be a very difficult objective to achieve. So we have to be careful how high we set the hurdle here. He said that we want to seriously reduce Iraq's nuclear, biological, chemical capabilities, and I think we can do that.

MARGARET WARNER: Do you agree, Admiral?

ADMIRAL LEIGHTON SMITH, U.S. Marine Corps (Ret.): I do, indeed. There is a considerable amount of fire power out in the Gulf right now in countries adjacent to it. The weapons that we have today are better; there are more of them. The F-18, the Tomahawks, the HARMS, the F-14's with the capability to drop weapons.

But most importantly, I think we've made improvements in our ability to operate with the Air Force in a combined effect--the joint operations together. And while we'd like to have all of the aircraft in the area available for the strikes, the true fact of the matter is that with our improvements in our communications command and control, with our better weapons systems, the fact that we're operating so much better together, I think that the synergistic effect of all of that really gives us a tremendous amount of firepower, and I think we can do exactly what the President wants us to do.

MARGARET WARNER: General Sheehan, how do you see this in terms of the possibility of the success, however we define it, or how the President defined it?

GENERAL JOHN SHEEHAN, U.S. Marine Corps (Ret.): Yes, Margaret. I think what Saddam Hussein has to realize is that one of these days he's going to go to bed and wake up there with a lot fewer buildings standing around in Baghdad. As Admiral Smith indicated, and General McPeak indicated, the technology we put into the weapons systems and the platforms we have in the region are much better than they were in '90 and '91.

In addition to that, we know more about Saddam Hussein and his forces than we did in '91 during the Gulf War. So the combined effects of that kind of capability leads to a very lethal punitive attack on Saddam Hussein's capabilities.

MARGARET WARNER: General McPeak, tell us what your sense is of how military action will unfold. What are the targets going to be? How good is our information about those targets? How good is our likelihood of hitting those targets?

GENERAL MERRILL McPEAK: Well, the first objective has to be to beat down the air defenses. We did that at the beginning of Desert Storm with a massive attack that paralyzed the surface to air missile threat in Iraq and also the hostile interceptor capability. So this is going to be a little tricky, but in the very opening minutes of whatever we do, we simply have to get these--the air defenses defeated.

And once they're defeated, we have to keep them down with more or less continuous around-the-clock pressure. And once you get the air defenses suppressed, you can take out the other targets at your leisure. You're free to operate in Iraqi air space and you can take the targets serially in a row, however you want to do it.

MARGARET WARNER: General Trainor, your sense of how it will unfold, and explain why Saddam has air defenses again if we took them out before the Gulf War.

LT. GENERAL BERNARD TRAINOR: Well, I think General McPeak put his finger on the first order of business as taking out his air defenses. But I think you'll see something of a replay of the opening night of the Gulf War, where it is a kind of a simultaneous air attack upon a number of key targets, priority targets, in addition to the air defense targets.

Now, his air defense capability is considerably degraded from that which he enjoyed during the Gulf War, the so-called Keery system that he had. Now, he's been able to cobble together a jerry-rigged early warning system with his radars. He also has air defense missiles. He has roughly 6,000 anti-aircraft weapons that could go against the U.S. aircraft, and that's why it's so important to put down that air defense capability to allow our pilots to fly with impunity.

And, of course, the Tomahawk missiles, which are not manned, will play a very major role in the suppression of the air defenses.

MARGARET WARNER: Admiral, give us your sense--you talked about how it was going to be different from the Gulf War, but, one, do you agree his air defenses are degraded? Do you think it will be relatively easy to take those out and after that, what are the targets?

ADMIRAL LEIGHTON SMITH: Well, first of all, I would never underestimate the enemy's ability to hurt us. He's got a tremendous integrated air defense capability. It may not be as good as it was during the Gulf War, but it's certainly a threat, and we have to honor that threat. I agree with General Trainor; we're going to see a lot of Tomahawk missiles going in there.

We're going to see a lot of HARM missiles going in there. We'll use whatever we have to use to take down that air defense. I think that ideally we'll go after targets that Saddam Hussein uses to maintain his power base. So my guess is we'll see a combination of hammering away at his defensive capabilities, hammer away at those things that give him power, the Revolutionary Guard, his armed forces, and then we'll also hammer away at what we can hammer away at with respect to the weapons of mass destruction.

Some of those are going to be buried very, very deep, and despite the fact that we've got very good weapons, once you get out of them, then you've got to worry about a collateral damage problem. So all of those have to play into General Zinni's mind as he develops his target list and develops his strategy. But I suspect we'll see a sort of across-the-board--they'll take them as they need to take them to put him in the most vulnerable position and put our forces in the most advantageous position.

MARGARET WARNER: Would you hazard a guess as to say what percentage of the weapons of mass destruction sites can be hit and taken out.

ADMIRAL LEIGHTON SMITH: Margaret, I don't know how many he's got, and so I could not even begin to approach--to answer that question. I can just tell you this. I would not want to be anywhere near where he has weapons of mass destruction stored because I would think that we know an awful lot about where they are, and I can assure you we can get--we can make him hurt hard.

MARGARET WARNER: General Sheehan, do you agree that the U.S. military probably has a pretty good idea of where these sites are?

GENERAL JOHN SHEEHAN: Clearly, there's been a very intrusive inspection regime conducted by UNSCOM over the last couple of years. Plus, as I've said, we've been watching the country and the Republican Guards and his forces now for seven years. So we know a great deal about it. We don't know where the yellow missiles are--we don't know where the Scud B missiles are, so--

MARGARET WARNER: And these are--let me just interrupt--these are missiles that would be capable of carrying such weapons?

GENERAL JOHN SHEEHAN: Absolutely correct. We do know that they exist, at least from the intelligence we have from the UNSCOM people, we don't know exactly where they are, so you can't target them. But what we do know we can target and we can target that within nine feet of an aim point from a thousand miles away. So that building is going to get destroyed.

MARGARET WARNER: Staying with you for a minute, General Sheehan, how would you say compared to the Gulf War and Admiral Smith talked about this--how much more accurate will our weapons, and how do you think it will compare--our ability to accurately find targets and take them out?

GENERAL JOHN SHEEHAN: I think in simple terms, Margaret, you can fire a Tomahawk missile, for example, an air launch Cruise missile, and you can hit within a very specific aim point and only miss it by nine feet. That's from a thousand miles away. So as we became better in terms of satellite technology in putting global positioning systems into missiles, we've increased the accuracy so a missile was fired an aircraft or a former ship, as a 90 percent probability of heating that aim point, as I said, within nine feet. That's very, very accurate.

MARGARET WARNER: General Trainor, your view on these new weapons or perfected weapons and how to change things.

LT. GENERAL BERNARD TRAINOR: There's no question. These weapons are magnificent. They were pretty impressive during the Gulf War; however, the amount of ordinance that was dropped on the Iraqis during the Gulf War, a very small percentage--about 4--I think 14 percent of the weaponry were the precision-guided munitions. The problem isn't in the weaponry. We have the weaponry to do the job.

The problem is in target identification and I don't think quite as sanguine as my colleagues are that we know where all of these targets are, or even where a substantial portion of the important ones are. But I think the President has taken that into account, and I think the Joint Chiefs of Staff had, and I think General Zinni, commanding in the area, has taken into account, and this is more than just going after the targets. This is going after Saddam Hussein's capabilities, and sending a very, very strong message to Saddam Hussein that if he keeps up his mischief, he's going to suffer for it, and those things that he holds dear to me are going to be put at risk, and this signal is going out to other rogue nations around the world.

MARGARET WARNER: General McPeak, another big difference from the Gulf War would be Saudi Arabia's apparent decision not to let the U.S. launch strike aircraft from there. How much of a difference--what would be the impact of that?

GENERAL MERRILL McPEAK: Well, that makes a substantial difference, no doubt about it.

MARGARET WARNER: Why?

GENERAL MERRILL McPEAK: Well, we simply won't have the order of battle of combat aircraft in there that we had during the Desert Storm. As a consequence, the Navy's going to have a much bigger role to play and Air Force support of the Navy will be important. I agree with--I think it was Snuffy Smith that said one aspect of this we look at as a big improvement is we were working together much better--Air Force airlift--flying in the personnel and logistic support; Air Force tankers helping refuel Navy aircraft, giving them the range to get into those deeper targets, space systems overhead, providing a battle damage assessment and intelligence--all these systems working together with Navy--predominantly Navy--but some Air Force fighter aircraft actually delivering the punch is going to be, I think, a much better version of how we operate jointly together in situations like this.

MARGARET WARNER: General Sheehan, let's go back to a topic that a couple of you raised and Admiral Smith did, which has to do with risk, that is, risk to U.S. troops and also to Iraqi civilians. How great are those risks? How can they be minimized? What do you expect on that score?

GENERAL JOHN SHEEHAN: Every planner that does strike planning worries about collateral damage.

MARGARET WARNER: By that, you mean civilian casualties?

GENERAL JOHN SHEEHAN: Civilian casualties, casualties to buildings that don't fit within the battle scheme of the target list. Every single planner worries about that. But by the time you fire a missile, release a bomb, a lot of things can go wrong. Environmental, technical problems--so it is going to happen. There are going to be instances of collateral damage, civilian casualties, and there are going to be cases, has been indicated because of the density of ground fire that aircraft will be exposed to over the target area, we will lose aircraft, and there will be civilian casualties in this fight.

MARGARET WARNER: Do you agree with that, Admiral?

ADMIRAL LEIGHTON SMITH: Well, it's almost unavoidable when you start throwing that much ordinance around, but let me just make a quick point, if I might, Margaret. We've talked about all the weapons systems and the technological advances and the way we're operating together better. There's an element that we haven't talked about, and that's the people out there doing the work. Tony Zinni is one of the best, smartest military people I've ever met in my life.

MARGARET WARNER: The commander.

ADMIRAL LEIGHTON SMITH: He's the commander in chief of the forces over there. We could not be better served by having that gentleman at the lead, and I can assure you that the people that I know are out there, are comfortable that he's going to look after him. He will know that there's risk involved; he will try to minimize that risk; but we all know that military people get paid from time to time to take that risk. The thing we have to understand is we have to stay the course. I guarantee you, the people are working hard to minimize any collateral damage, to utilize everything the industrial base of this country has given them to carry out the President's wishes. I wish 'em well.

MARGARET WARNER: General Trainor, do you think--how much--to what degree do you think both the U.S. troop damage and civilian damage can be contained or minimized?

LT. GENERAL BERNARD TRAINOR: I think you have to make comparisons and comparisons with previous wars and engagements. We have been very, very careful over the years to develop weapons and develop targeting systems and develop targeting policies to minimize risks to the pilots and risks to the civilians. When you compare what we were able to do during Desert Storm with the sort of thing that went on in the Vietnamese War or even more so in World War II, the difference is astronomical. We have really reached a level of sophistication and precision that serves the interests of the U.S. military's objective but also the interest of the innocent civilians that happened to be in the rogue state.

MARGARET WARNER: General McPeak.

GENERAL MERRILL McPEAK: Well, even one civilian casualty is too many, and so we will work very hard to minimize that. One of the reasons is that Saddam Hussein will make sure that we see on CNN or the nightly news any pictures of women and children that are killed inadvertently in these attacks, so it will work against us in the--in the arena where we have to raise public support.

But, you know, when you compare it, as Nick Trainor says, to a firebombing of Tokyo or what the RAF did to Dresden in World War II, you're talking about miniscule casualties even in Desert Storm, the Iraqis, themselves, only claim a couple of thousand civilians inadvertently killed--during Desert Storm it was quite easy to tune into CNN during the daytime, live broadcasting scenes from Baghdad, people sipping coffee in restaurants and so forth, so this is a different kind of air warfare, much more discriminate, nevertheless, there will be casualties; we'll work hard to avoid 'em.

MARGARET WARNER: All right. General McPeak, General Trainor and Sheehan and Admiral Smith, thank you all very much.