... What is it that made them [the Sept. 11 hijackers] do it? ... Was it their commitment? What is it?

It's their version of the Islamic faith and their view of the world. When I first began to work against these guys, really, in post-1993 along with a lot of other FBI and CIA people ... I did a lot of reading, like a lot of other guys. But I really came to understand that they're thinking back 1,000 years. They're thinking back to the Crusades. They view the world in those kinds of terms. They are very fanatically committed to their religion. It's not the Muslim religion; it's their religion, their view of Islam -- and that view of Islam is world domination, the whole world being an Islamic republic, with them at the helm of that world.

So it's pretty frightening, and I don't think there's anything worse in terms of terrorism. ... So I was not shocked in terms of the fact that they conducted this attack. I wasn't surprised that they would do an attack of this magnitude. I just felt, I think like a lot of guys that had worked against them, just a sense of, "God, what could we have done better? What else was there to do that could have prevented this thing?" ...

Did we underestimate Al Qaeda?

I don't think we underestimated Al Qaeda in terms of the lethality of the organization and roughly the goals and objectives of the organization. But in terms of having the kind of knowledge we needed, the kind of key intelligence that would have prevented that thing, we didn't have it. Is that underestimation? I don't think it is. I just don't think we have the information that we needed.

Is it an intelligence failure? I've certainly thought about that a lot. I don't know, because I don't know what we actually had in hand in the couple of years prior to this happening. This was a long-planned operation and, as we're seeing now, a lot of it was done in Germany. I just can't understand clearly how an isolated small group, very, very conscious of operational security, could do this.

How did they slip under our radar screen?

A lot of these guys came here illegally on visas. They certainly were very careful people; they blended into the community. Obviously, they knew essentially how the U.S. works. They knew how to travel, they knew how to use ATM machines, they knew how to find things. And they kept to themselves. They were careful. They did things that normal 20- and 30-year-old people would do, went to places that were very normal for that age group. They just blended in very, very well. They had obviously been trained well. So unless they did something that would come to the attention of law enforcement or unless there was credible intelligence developed through information abroad or sources here, they could operate pretty freely -- and they certainly did.

They seemed to be very cunning about their knowledge of our weaknesses and how to exploit our society. Talk about that for a moment.

... I think it goes back to the time when, during the Afghan war, people from many countries were recruited, trained, and fought in Afghanistan and then returned to their countries. And certainly the United States was one of those countries. And there were a number of places where people were recruited like the Al Farooq Mosque up in the New York area, the Al Kifah Refugee Center, another place up on the New York area where people were identified, recruited and again sent over and came back.

So there have been people here in the United States for a long period of time who clearly understand the country, are citizens of the country, are residents of the country. So there is that kind of information flow available to Al Qaeda, and has been available to them for some time.

You talk about cunning; yes, they're cunning because they understood it. They understood (a) how to get in here, (b) how to blend in, (c) how to find flight schools. I mean, all these things they understood. I think one of the leaders, Mohamed Atta, spoke English. I'm sure others spoke English. So they just knew how to work the system.

Are you saying that this group of 19 hijackers had a support network? ...

I think that's a strong possibility. But even if that support network wasn't here, even if they didn't tell them where to go and how to do it, what I'm saying to you is that there was enough intelligence gathered by Al Qaeda through people who had lived here over many years that they could have figured out how to do things pretty easily. ...

What do you make of the way the INS handled [Mohamed Atta], who is in and out on a tourist visa, even one that has expired?

Well, you know what -- I'm not surprised. And I'm not trying to be critical of the immigration service. But when you're an immigration officer and you're sitting there and you've got two or three 747s that have just landed and you're processing 1,200-1,500 passengers at a crack and a guy presents that looks good, is dressed well, good personality, you look at his passport and he just looks like a young businessman to you, and he comes in.

Did they goof?

I don't think they goofed. I just think it's an impossible situation.

This is an expired visa. And he says he's a tourist, but he's going to go and be a student.

When a guy comes in on an expired visa, that is a goof. But you know, even going back to Ramzi Yousef, I think he came in on no paper and they had so many people in the holding facility that night that they let him go with a notice to appear on a certain date. Of course, he never appeared. [Editor's Note: Ramzi Yousef was sentenced to life in prison in 1997 for masterminding the 1993 World Trade Center bombing.]

So the kind of controls that we would like to see there, the kind of capability just to hold people -- they're not in place. I'm hopeful that with this new proposal to split INS into an enforcement branch and an immigration branch, that it might get harder. But I'll tell you, it's not easy. And there hasn't been a whole lot of attention, hard attention, placed on this over the last many, many years, in my view. ...

You keep saying this is Al Qaeda. What are the two, three, four pieces of key evidence that say to you without question [that] this is Al Qaeda?

... When I saw the attack, I instinctively felt it was bin Laden, but mainly because I think I understand those guys a little bit. ... The twin towers, to them, are the symbol of our economic society. It was always that way, and the symbol of our support to Israel, which they hate. So for them that was always a big thing, and that was why they wanted to hit it the first time in 1993. The Pentagon, the White House, again the Capitol, the symbols of our government, the symbols of our way of life, these were symbols of our government, the government they wanted to bring down. They're very symbolic people, and have been throughout my experience with them. ...

Was [there] something that surfaced that could have rung alarm bells, that might have led to a chain of events that would have unraveled this, or at least unearthed part of it? I'm thinking specifically of the arrest in Minnesota of Zacarias Moussaoui. ... If a flight school had called you and said, "Here's a guy who wants to fly modern jets and he's not even qualified as a pilot." ... What does that say to you, and how do you read it?

Had that information come to me in either one of my old jobs, I would have been terrified. I would have just very, very immediately seized on that and had absolutely a full-court, extremely intensive investigation of that person and certainly checked him with everybody that we knew at CIA and would have asked CIA to run checks on him to see who the heck he is. I mean, that would have been our worst nightmare. Certainly my worst nightmare is somebody hijacking a plane, just even hijacking a plane and taking hostages. So that's probably the first thing that would have entered my mind: this guy is trying to set up a hijack.

In terms of crashing a jet into a building, it might have been in the recesses of my mind. But I would have immediately thought "hijack" and gone into the prevent mode in terms of finding out who is he, who is he with? Does he work? Does he have contacts here in the United States? I'd want to know everything about him from the day he was born.

Then the French come in, 10 days later. ... They hand you a bundle of information -- you the FBI -- which says this guy is connected with Islamic militants and terrorists, if not Al Qaeda directly. What does that say to you? How do you react to that?

... I think with the French providing more details in terms of the activities of Moussaoui, that would have ratcheted me up even higher in terms of this guy. Again, I would have wanted to know everybody he knows, particularly everybody he knows in the United States right now. What has he been doing here? How long has he been here? What are his movements? Who has he been in contact with? Does he have a telephone at his residence? Are there toll records? These kinds of things. ... Are there others taking flight training like him? If they are, who are they, where are the schools? Those are all the things that would just rattle right through your brain almost immediately. I'd certainly think within an hour you'd be thinking about all these things. ... Now, whether that was done or not, I don't know. ...

Tell me about what you knew about Murad and that interrogation. [Editor's Note: Abdul Hakim Murad was convicted of plotting in January 1995 to bomb 11 airliners from the U.S. over the Far East.]

I do know that back in 1995, one of the subjects in what the FBI calls Manila Air -- the plot to blow up about a dozen airliners in the Philippines -- when he was interviewed, he talked about himself crashing a plane into CIA headquarters. But my recollection of this wasn't a major passenger airline. This was an extemporaneous statement by this guy. It's something he wanted to do. But I never had any information back at that time that anyone else was thinking about doing it. I think we all thought it was just this one guy talking. ...

What about Mohamed Atta as an operational commander? How much discretion do you think that he had? ... How might he have related to others higher up and perhaps had the overall strategic view? ...

He would have had limited discretion, in my view. He would have been charged by the leadership to go and do this. They would have talked about it extensively. They would have spent a lot of time thinking about this, how to do it, how to get into the United States, how to live in the United States. There would have been a lot of pre-operational discussion and planning to pull off an operation like this and to be successful.

So while I think he probably had some operational discretion in terms of logistics like apartments and selecting places to live and selecting rental car companies and these kind of things, I think when it came down to the nuts and bolts of actually doing the operation, he would have had to have gone someplace, met, discussed, agreed. They had to agree on the timing of it. A lot of these variables, I think, would have been pinned down. But he probably would have had discretion to abort it, if something happened. Let's say that they had gone to the airport that morning and they didn't make it through security, there was a major problem with them. He probably would have given someone the high sign to get in touch with everybody else and say, "Stand down. Do it another day." ...

We know that Mohamed Atta made many trips back to Europe, even once he was here in the United States learning how to be a pilot. What is the significance do you think of those trips back to Europe, particularly in the weeks immediately preceding this?

... I think he was getting direction. I think he was going back to report on the status of where they were in the operation to make sure that they were secure in terms of their operational security, and think he was getting direction to move ahead, and probably authorization to move ahead.

From some key figure?

Yes, from somebody that was involved in this thing that he was reporting back to.

And this would have been done in person rather than ...

Definitely in person, rather than the telephone and risking discovery. It's, again, good operational security face to face, probably in an area where they couldn't be overheard. Some secure location that they were convinced were secure and again this one-on-one exchange.

And what does that tell us about the importance of Europe in general to the Al Qaeda network? ...

Well, what it tells me is that there certainly is an infrastructure in place, a support infrastructure, maybe even somewhat of a command infrastructure. And Al Qaeda and their associates have been able to establish an excellent network in Europe, certainly in Germany, certainly in the U.K., probably Spain, probably other countries. I think Italy is also another place where we've had this kind of activity in the past. So there's a pretty well-established network of support. ...

Ultimately a group of 19 were together here in the United States for this operation. What are your views about the way that group broke down? ... How would you describe them? Would you lump them roughly into two groups? ...

In terms of their structure here in the United States, I really see it as a leadership element and then a soldier element. The leadership element controlled the operation and the rest of the guys followed. ... Probably if you look at the educational background and sophistication of the leaders versus the others, you'll find a pretty sharp demarcation line. Some guys were well educated, fluent in English, really were sharp; other guys weren't. ...

Without question, all of these guys were handpicked people for various reasons. Obviously their leadership and intelligence, the ability to learn to fly these multiengine aircraft. That's a pretty sophisticated individual. I think everyone recognizes that. In terms of the rest of them, they had to be very fervently committed to their religion and to the mission and they had to be convinced that giving up their lives was the best thing for them in this particular operation. Nineteen of them! I mean, 19 of them volunteered to kill themselves! ... And no one cracked. Of these people, no one came in and said to the law enforcement, "Hey, I'm part of this group, and I'm not going to do this." They all did it, which really, to me, tells me that their selection process was very good. ...

What was specific to the 19 who were chosen by and large was their clean records. Reflect on that a bit, if you like. ...

The 19 hijackers were clean, they weren't criminals. They had clean records; they had clean paper. There were no significant warning signs in their backgrounds that would have focused law enforcement or the immigration people on them specifically. ... Even if one or two of them had been focused on significantly, again, in checking them out, you would have found nothing, so you had really nothing to go on. So they're here and many of them here legally, some here not legally. But I think the majority of them came in on good paper. There's thousands and thousands of people that come in here every single day from around the world, and how can you focus in laser like on people that are here on clean paper? It's impossible. ...

We know that Mohamed Atta went to Prague on at least two occasions and met a known member of the Iraqi intelligence services. What might that suggest?

You know, that's really interesting to me. First of all, because the intelligence service representative ... wasn't an underling; he was the head guy of Iraqi intelligence in Prague, probably for a wide operational area, and that had to be important. I really believe my colleagues would see that as just a very, very important meeting. What was it about? Why is this guy in contact? Multiple times he's in contact with him, which says to me [a] relationship -- probably either he's trying to develop him as a source, a human source, or he already is a human source for the Iraqi intelligence service.

The question is, what is he? Was he an Al Qaeda guy who had been recruited by the Iraqis and providing intelligence to the Iraqis about Al Qaeda? Maybe. It's not logical to me, because the guy ultimately killed himself for Al Qaeda. So it's a real big issue, at least for me, to know what that relationship was. ...

We know that Mohamed Atta was interested in crop sprayers. He went to Florida. He was very interested, very persistent, he wanted to get in and find out what they could do, what their capabilities were. What does this suggest about plans that he had and that the group had?

Well, certainly when Mohamed Atta was looking at crop-dusting planes, you have to immediately figure that he's going to want to spray some kind of agent on people and do a lot of damage. It had to be that. I mean, there's no other logical conclusion you can reach now. ... His interest in a crop duster could have been intelligence gathering for the future, rather than right now, because he's obviously got his orders. He's obviously fully engaged in planning the World Trade Center, the Pentagon and something else attacks. But for some reason, he's out there looking at these other aircraft, so I think that's very significant. ...

We know also at about that time he was looking possibly in Norfolk, Va., at American warships; scouting again. Is there a sense that Mohamed Atta was the man on the ground? ... That he was a real gatherer of intelligence?

I'd have to conclude that, based upon the fact that he did look at crop dusters, he did look at Norfolk; he was very active scoping things out. They could have been planning another attack against a warship here, ... getting the feel of the land and whether or not they could do it. There is tremendous pre-operational planning that goes into any of these things, but particularly these guys, they spend a lot of time scoping things out. So, yes, he may have just been gathering intel to send back or to report on in response to a task.