... People will say, "Well, we didn't think we were vulnerable in our homeland. We didn't think you could export terrorists. We didn't think you could put people in the field as they did for 15, 16, 18 months." Were there elements of this that were a surprise to you?

Oh, I think for sure. The ability to coordinate an attack of that nature and to provide the logistics for it for an extended period of time to me is shocking. The fact that they went undetected, were able to go into flight schools and learn how to fly planes without the necessity of taking off and landing, the ability to infiltrate and to communicate amongst one another certainly does come as a surprise. But I think it's the magnitude of the devastation that they caused as opposed to their ability to carry out violence. ...

So what was the problem? We didn't anticipate the kind of attack?

I think precisely -- the inability to anticipate the hijacking of large airliners fully loaded with fuel and fly them into the upper towers of the Trade Center was not something that was anticipated. ...

When you reviewed the potential threats that terrorists wreak on a city like New York, where you were based -- whether it's bioterrorism, traditional explosives, truck bombings, what-have-you -- did the repertoire of potential threats that you worked over with your office and staff include something like this?

We in New York were very, very fortunate to have one of the largest, and I think the oldest terrorist task forces in the country. ... That task force worked several bombing cases to include the Trade Center, East Africa, and several catastrophic airline events to include Egypt Air and TWA 800. So it was a group of people that unfortunately had tremendous experience in these types of disasters. ... [I]n my time there, we went through a lot of pains to prepare for a host of different eventualities. And I can assure you we did not anticipate nor plan for the type of event that occurred on Sept. 11. ...

If you look at the hijackers' operation, when you look at their tradecraft, what are the secrets of their success from their standpoint? What was it they did that enabled them to pull off this simultaneous coordinated terrorist attack?

I think there were several things that the terrorists were able to do. One is they were able to sustain themselves in the United States for a period of time. They were able to blend into the community without drawing excessive attention to themselves. They were able to provide the logistic support necessary to keep them here for the year or so that it took to get that kind of training, and they were able to do it under the veil of law enforcement for a period of time and they went undetected.

I think if there's any surprise to me, it's their ability to communicate that we did not pick up on, because it did require a fair amount of communication and coordination to be able to do that. So it is my belief -- and I'm speculating, to some extent -- that if there was a failure, it was a failure to intercept the communications that perhaps could have been a warning to this event.

But they obviously were very successful in their ability to hide for almost a year while they were here, and to, again, develop the logistical support that led to the events of Sept. 11.

I wonder if you see them as experts of finding our weaknesses and exploiting them. We run into them going to car rental agencies that don't have software that keep records of traffic violations. We find them going to flight schools that don't seem to check into their background. We find them slipping through the INS with explanations that seemed to satisfy people on the spot. ... They seem to know a great deal about our vulnerabilities and where they can exploit them, and we have a great deal of difficulty finding their vulnerabilities.

Certainly we are, as a nation, vulnerable. But that vulnerability is really born of the freedoms that we enjoy here. We do not live in a society that closes its borders. We have relatively open borders. We allow people into the United States on relatively easy access, both legally and illegally. We keep our institutions open in terms of information and freedom of information. We allow people to basically come into the United States and travel freely about without any national identification card, without the ability to track people as they move about. ...

What kind of training do Al Qaeda terrorists get, for example, that would be relevant to the operation that we saw here on Sept. 11? ...

Certainly the type of training that they would receive, again in Afghanistan and in other places, would be compartmentalized. Somebody would be responsible for logistics. Others would be responsible for the tactical deployment. Others would be responsible for flying the plane, and they would be done for a purpose. ...

For example, those that were responsible for gaining access to the plane by overpowering the passengers would have received training in that regard. If explosives were to be used in additional attacks, they would have received training in that regard. Those that were to be responsible for the financial support of the group and their ability to blend in would be directed in that regard. So it is a very, very unique and complex system. But unfortunately, it has been successful in several attacks that we've had to deal with.

Afghanistan looks like a fairly primitive place; this looks like a fairly sophisticated operation. Does this training that they get in Afghanistan include handling finances, the international banking system, how to get along in a Western country, the whole business of shaving your beard and going local and looking modern? ...

I think [it would be] a terrible mistake on our part to underestimate their ability and their resolve. We're talking about a group of people that were really born in the conflict with the Soviet Union in the 1980s, a group of people that really get their history from fighting with the mujahedeen and expelling from their country the largest standing army in the world. To me that represents, I think, a tremendous amount of resolve, a tremendous amount of imagination and a tremendous fortitude. So when you look at training, when you look at their ability to assimilate into the United States and their commitment to the extremist movement, I think it's important to understand the history of Afghanistan and the history of the people that came out of that. ...

Their ability to assimilate into the United States and into societies around the flight schools and around the logistics of that were also done in a way that avoided detection. And the other thing that they do is they understand our techniques. Every time we have a trial -- and we've had several terrorist trials -- the government, through discovery and through the nature of our court system, educates them in very minute detail as the techniques we employ to overcome their efforts and to gain detection of the events that are surrounding them. So I would not underestimate them for one minute.

If you could quickly, for a general audience, tick off what you see are the trademarks and the connections of Al Qaeda and bin Laden with this bombing attack on Sept. 11, what were the key elements? ...

One is their ability to operate in compartmentalized cells; their ability to travel back into Germany, back into London, in order to receive both instructions and training. ... Their ability to operate in secrecy, and their ability to establish communications amongst one another in a rather surreptitious way to avoid detection. So a number of factors came together. Certainly their ability to coordinate their efforts on Sept. 11 to cause the kind of casualties that they did, very similar to the coordinated attacks that occurred in East Africa against the two U.S. embassies. I think that there are many similarities in terms of the types of tradecraft and the logistics employed both on Sept. 11 and in the East Africa and USS Cole disaster.

When you see Mohamed Atta returning to Germany in the spring of 2001, or going to Spain in July of 2001, what do you see him doing there?

I think when Atta traveled both to Germany and traveled to Spain -- again, I rely on what has been historically the reasons for these types of trips -- they're receiving instructions; they're gaining intelligence information; they're certainly understanding the logistical nature to receive support and developing financial contacts for the rest of the people that are in their cell. So I think that type of travel and the ability of law enforcement to go back and understand who was contacted on these trips and what type of support was gained is critical to an understanding of the network that Al Qaeda employs.

So who, or what type of people is Atta meeting in Germany or Spain?

Again, I will speak in very general terms as far as what my belief on those trips. More than likely, when he traveled, he probably met either directly or indirectly members of Al Qaeda. He probably received instructions from the hierarchy associated with Osama bin Laden from his emissaries. He probably received instructions on who to contact for financial and logistical support. Those trips were critical, in my mind, to the success that they unfortunately had on Sept. 11.

You mentioned the communications several times. One of the things we noticed is they're going to public libraries. ... They go to Kinko's. They go to all kinds of anonymous places to hook themselves up to the Internet. What's going on here? What's happening? ...

Assuming that they get on the Internet and have the ability to communicate amongst one another, it's my belief that that's what they did -- establish e-mail communication. And I speculate as to that. But they are providing instructions. They're providing timing instructions. They're providing instructions as far as financial support, and they're providing overall direction to the nature of the operation that was to occur on Sept. 11.

Why can't we find that out? Why can't we spot that? Do they have codes? I've heard they had software that actually erases their tracks when they finish. What is it that makes that so hard to crack?

Again, I'm not a technical expert, but you have to understand the number of e-mails and communications that are sent in this country every day. There is no one in cyberspace that's monitoring each one of these things on a real-time or on a minute-by-minute basis. And certainly they understand that. The ability to change direction, and the ability to change the way they communicate, is certainly different than it was even five years ago. When you look at cellular technology and the ability to go into a store and get a digital phone, use it for 30 days and get rid of it, certainly makes the ability of law enforcement to intercept critical communications almost impossible.

You tie that in to the ability to walk into a Kinko's and get on a computer and communicate via e-mail for a short period of time and walk away from it, and perhaps have the ability to erase that communication from ever having occurred. Those techniques or that tradecraft was critical, in my estimation, to the events of Sept. 11.

You have a flight school in Minnesota. A guy by the name of Moussaoui shows up. He wants to fly a plane but he doesn't care about landing and take off. He wants to know how to get into a cockpit. An alert flight schools says, "Wait a second, this is unusual," [and] gets in touch with the FBI. Does that ring alarm bells that something unusual is going on?

It certainly should have. And as my understanding is, they did detain Moussaoui as a result of that information. But again, to tie that into a broader conspiracy, to tie that information into directly affecting the events of Sept. 11 was not something that they were able -- again from what I've read -- to complete. ...

I'm going to take you back to the days when you were an agent and very involved in this, right back in fact to 1993 and the World Trade Center bombing that time. From the work that you did in the wake of that in trying to solve that, and the associated plots which came out of it, what would you say was the significance of that particular target and their determination to get to grips with it?

I think certainly when you look at the Trade Center, both in February 1993 and as of Sept. 11 of this year, they stood as symbols of really the financial [strength] and freedom that the U.S. enjoyed. They were hallmarks in New York City. They were landmarks for people that saw them every day. The attempts that they had in 1993, I think, were really an attempt to strike at the very heart of the freedoms that we enjoy, and to topple what I think stood as really the symbols of U.S. industry, and to really send that message back that terrorism has reached our shores. ...

It was ironic ... that one of the individuals involved in the plot in February of 1993 was an individual by the name of Ramzi Yousef. Unfortunately, he was able to escape after the bombings occurred, and we located him in Manila in the Philippines as he was in the middle of a plot to bomb 11 U.S. airliners over the Pacific Ocean. Fortunately, he was apprehended.

We brought him back into New York and had the responsibility of transporting him down to the Metropolitan Correctional Center in Lower Manhattan on the day he was brought back. And I'll never forget this. He came off the plane. He was blindfolded and in handcuffs, and we put him on a helicopter to fly him down the Hudson River towards the jail. We took the blindfold off to allow him to focus his eyes, and it was ironic, because he finally focused as the helicopter flew in front of the Trade Center.

One of the agents on board that night said to him, "Do you see? It still stands." And he said, in very chilling terms, "It would not have been had we had more money." And I took that in a very, very significant way to mean that they were very dedicated to the extremist cause that they represented, almost to the extent that it became something that I don't think we, in the culture that I grew up in, could really understand.

Do you think it was a sense of unfinished business, the World Trade Center?

Very much so. ...

So do you think, for Al Qaeda, bringing down the World Trade Center was something that festered, as it were? Something they felt they had to achieve long term, and that was the ultimate goal?

I'm not certainly a cultural expert on Al Qaeda. But from what I would gather, the purpose of this really was to unite the Muslim community in a so-called jihad or holy war against the United States. ... I'm convinced that the purpose in the attack on the Trade Center was to galvanize the so-called extremist movement in the Middle East against the United States. And if that should happen, then they may have succeeded. ...

Obviously we know that they came here to America but that they, if you like, had their ideological spark, their training, in Germany. Do you have any views at all on the way that Europe factored into this?

... I think it's important as the case unfolds and for a better understanding of how it actually did develop, to understand what contacts [Atta] did make when he made his trips into Germany and into Spain. And that would be critical to understand what role those countries played. More than likely -- and I'll speculate for a minute -- his visits to Germany probably involved some direction from the hierarchy in Afghanistan and their ability to communicate with him while he was in Germany.

What overall role would the hierarchy in Afghanistan have played? I'm talking here about perhaps choosing the ultimate targets, giving the ultimate military planning and direction.

I think we saw it in Somalia -- and again I'll speculate for a minute -- that we probably would see the same thing as far as the choosing of the target, the choosing of the Trade Center for a symbolic value. The overall support of the operation, the ability to approve the attacks that occurred on Sept. 11, I think in a very real sense was the responsibility of the hierarchy of Al Qaeda in Afghanistan.

At the end of the day, do you think that the events of Sept. 11, the attacks, represented somewhat of a failure of imagination on the part of law enforcement and the intelligence community? Because parts of the puzzle were there; there were clues, but somehow nobody could put them together.

That's a very, very difficult question. I think it's also important to understand that, as far as Osama bin Laden is concerned, he made no secret about his hatred of the United States and his ability to promote a jihad that called for the killing of Christians and Jews associated with supporting the United States and its role in the Middle East.

So I don't think it should come as any surprise that there was a war that he had declared on the United States. He avowed to destroy U.S. institutions. That was a very public proclamation on his part. We saw it after East Africa. We saw it after the USS Cole. So I think as you understand his teachings and his so-called extremist views, the fact that they came back for a second time and attacked the Trade Center, successfully in bringing it down, was probably more a failure of our ability to react proactively to that than it was as a failure of intelligence. To the extent that any law enforcement agency had specific and credible information on an attack of that nature, it would have been prevented.

It's now easy to sit back five weeks later and say, "There were clues." Sure, there were clues. But those clues occurred over years. There wasn't a week that went by [that there wasn't] some threat that would come out of either bin Laden or associated people with him, and we took those very seriously.

But you could really only react when it came together in terms of specific targets and a time frame that would allow law enforcement the ability to neutralize that threat, and that did occur. It occurred in Manila. Those airlines were prevented from the kinds of attacks that occurred. It occurred during the millennium celebration and the role in Seattle. So we did have some successes in preventing the kinds of acts that were designed to kill and maim people. It did not occur on Sept. 11 for a lot of different reasons.

So where were the weaknesses in the system?

... There are a lot of things that, as we look at putting additional resources in this, probably will happen from this point forward. And there very well may have been an inability to assimilate information in a timely fashion, disseminate it and use it. But again, understanding the amount of intelligence that's developed out there on a daily basis, this was something that just probably went through the cracks.