This is a partial transcript from "On the Record," August 10, 2006, that has been edited for clarity.

(BEGIN VIDEO CLIP)

GEORGE WALKER BUSH, PRESIDENT OF THE UNITED STATES: It is a mistake to believe there is no threat to the United States of America. And that is why we have given our officials the tools they need to protect our people.

(END VIDEO CLIP)

GRETA VAN SUSTEREN, HOST: We're back live in London. It's about 3:30 a.m. here, and behind me, of course, is Heathrow airport, with those planes that would originate had this plot never been thwarted. They would have come right out of this airport headed to the United States. And of course, those are jumbo planes that fly across that ocean.

Peter Brookes, former CIA agent, joins us. Peter, how did this plot get thwarted? What — what did they — what did they do right this time?

PETER BROOKES, FORMER CIA AGENT: Well, I think what happened, after last summer's tragedy in London, the 7/7 attacks on the subways and the buses, I'm sure that the Brits started looking at communities in their country that might be full of radicals. So they probably started looking at getting informants to keep an eye on these people. And it turns out that they probably were watching some of these folks. And then we got a tip from Pakistan, or at least, that's the way it appears right now, that really set them onto looking at a group of people and then people beyond that. And it looks like we were successful this time.

VAN SUSTEREN: I guess the important factor is the human intelligence element. If an undercover U.K. — British intelligence was able to do this, I mean, that's — that's the best sign, that we can infiltrate these groups, isn't it?

BROOKES: Absolutely. That's critically important. I mean, you know, technical intelligence is wonderful. It's all sorts of bells and whistles, satellites and other things. But once again, human intelligence is critically important, having somebody in the room, looking at the body language, able to see the documents. It's something you really can't get from — maybe from an intercept, which are good, as well, or photography from a satellite or something along that line. So having somebody inside is really critical.

Also, somebody on the inside can ask questions. You know, a satellite can't ask a questions or, you know, an intercept, an electronic intercept. They only get what is being said. But an inside informant can certainly ask questions beyond the basics that would perhaps give us some clues about future operations.

VAN SUSTEREN: You know, Peter, 24 arrested. And they were wanting to take down 10 airplanes going across the ocean. That's phenomenal. I mean, it — what does it tell you about sort of this organization?

BROOKES: Well, it's rather sophisticated. I mean, thinking about it five years out — and I think one of the things that officials were really shocked about was the sophistication, the in-depth planning, the coordination. I mean, this was a big group. I mean, you know, Usama bin Laden kept the 9/11 attack pretty small. It was originally, out of the 19 — mid-'90s attacks, the operation Bojinka in the Philippines, they were talking about 10 planes. Usama bin laden shrunk down the 9/11 attacks to four planes. But these guys expanded it again. So we're maybe talking about maybe as many as 50 people, 50 extremists, 50 potential terrorists that we're dealing with here. And I think that is pretty incredible.

VAN SUSTEREN: Indeed, it is. Peter Brookes, thank you very much.

BROOKES: Thank you.

VAN SUSTEREN: We turn now to Bill Gertz of The Washington Times. Bill, the manhunt is on, 24 picked up for what would have been a spectacular act of terrorism. What about this manhunt? Do we have all of them, or could there have been as many as 50, as Peter Brookes suggests? I mean, where do we go from here?

BILL GERTZ, WASHINGTON TIMES: Well, Greta, there still is an intensive manhunt for people they think are left over from the original plot. Intelligence officials told me that these 24 people, and these 50 that are involved, are not directly involved, that they're a combination of types of people. A lot of them are the hard-core al Qaeda people from Pakistan, and others are home-grown — that is, people who provide logistics and support for the operation.

And they're cellular in structure. That is that each of these groups was planning to go after as many as 10 aircraft. So you had small groups that were planning to smuggle these liquid explosives on board, try to set them off in a place where it could cause catastrophic damage to the plane.

VAN SUSTEREN: Bill, do we know or have you heard anything whether the 24 who were actually arrested were the ones who were going to be doing this dry one in two days, and then of course, the act — the real thing a couple of days later? The 24 arrested, are these the people who were going to board these aircraft?

GERTZ: I think that the people who were going to board the aircraft are among the 24 people arrested. At least, that's my understanding from talking to people close to the case. They really did a sweep of everybody that was involved. They had, again, the British called it very intensive surveillance.

You know, the reports are that they had an agent inside the organization. You know, usually, in the intelligence business, when they say they have an agent, that's usually to mask the fact that they had electronic intelligence. And when they say they have electronic or technical intelligence, that's usually meant to mask the fact that they had an agent inside. So I think it was a combination of all of those. We know that the Pakistanis were involved, the British. Again, MI5, is very good. They've awoken to the terrorist threat after the 7/7 bombings last year.

VAN SUSTEREN: Do you know — Bill, one of the things that we haven't talked about at all so far is the — I mean, the components, this liquid explosive that was supposedly going to be brought on board these 10 transatlantic flights — do you know if any of the searches or the arrests — whether or not they picked up any liquid explosive?

GERTZ: Don't know that, if they've actually got materials. As much as I have been able to determine is that they know what the components were going to be, some kind of a sport drink container that was — had a special compartment for the liquid explosive. They were then going to use a flash camera as a detonator for this. So again, it's very rudimentary, very simple, but again, possibly very deadly when you're in the — inside a cabin of an aircraft at 30,00 feet.

VAN SUSTEREN: Yes, indeed. Terrifying and deadly, as well. Bill Gertz, thank you very much.

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