This is a partial transcript of The Big Story With John Gibson, August 9, 2004, that has been edited for clarity.

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JOHN GIBSON, HOST: The White House says there's nothing political about the latest terror warnings. There are people who want to kill us, and those people have to be stopped.

In addition to the warnings about financial buildings, the FBI says Al Qaeda (search) could try to use limos or rental cars as bombs in an attack. I'm joined by Jim Walsh, he's a Terrorism Analyst at Harvard University. Dr. Walsh, the big question: Do public terror warnings help prevent attacks?

JIM WALSH, TERRORISM ANALYST, HARVARD UNIVERSITY: Oh, I think they do, John.

I think that they can be very useful instruments in the struggle against terrorism. They get people focused, it does make them more vigilant, that's what the early data says; it certainly gets law enforcement focused. But, it all depends on how you do it.

They're really a double-edged sword: When they're done well, they can be a powerful tool, but when they're done poorly, they can undermine confidence in the system and actually make people more anxious. It's all about how you do it.

GIBSON: Well, is the how you do it, this whole business about breathlessly announcing information that is four years old?

WALSH: Yeah. That might have something to do with it. You know, I've been a critic of this terror warning system for a while and I'm not the only one. The Government Accounting Office has been as well.

But this past Sunday, I went on the TV networks and said this was a terrific improvement, that they were giving specific information and they were telling the American public how to handle it, and they were focusing the terror threat on specific areas rather than, people in South Dakota and Idaho wondering if Al Qaeda's going to show up. So, that was all good.

But then 24 hours later we find out that most of the information was four years old, and while still relevant, it sort of, undercut what they were trying to do.

GIBSON: Right. But, isn't that a cheap shot really? I mean, we know that Al Qaeda took years planning the September 11th (search) attack, years and years. So, if we find last week a collection of material that shows that they've been casing New York City or Washington for four years, why is that any less worthwhile than information they were doing the day before yesterday?

WALSH: Well, that's a good question, John, but there is actually a pretty good answer as well. It's not that it's irrelevant, it does provide us some evidence about their intention and the sorts of targets they would hit. But the reality is that, yes, Al Qaeda is meticulous, does years of planning because it wants to scope out the place. But when you have data that's four years old, that data is outdated.

In other words, the security regulations at Citicorp (search) or Citigroup and at those other buildings have all changed since 9/11, so if Al Qaeda's really going to attack them, they're going to have to go and redo that reconnaissance.

GIBSON: Well, right, but it tells you that they were looking at a certain building and that...

WALSH: Yes.

GIBSON: ... and that they're interested in the Prudential Building in Newark, New Jersey, the Citicorp Building in New York, the stock exchange down on Wall Street; that they're thinking about helicopters. I would think — correct me if I'm wrong — we would know if there were Mohamed Attas around the country taking helicopter flying lessons, wouldn't we?

WALSH: Well, gosh, I hope so. Given what we've learned from the various intelligence reports, not only the 9/11 Commission, but the Joint House-Senate Intelligence Report that came out in January. It appears as if there's still a lot of work left to be done to make sure that information is being coordinated and the dots are being connected. I hope not.

But, there is some good news, believe it or not. It's hard to believe. But good news in this stuff about helicopters and limousines. By the way, Al Qaeda always looks at these different things just because they think about a particular tactic, doesn't mean they'll use it, but if they go this route, that's actually better than them using truck bombs or airlines. Why do I say that?

Mostly the thing they're most likely to do is attack with conventional explosives: TNT, fertilizer, that sort of thing. But when it comes to conventional explosives, bigger is better. More is better. And so a truck filled with explosives is more dangerous than a limousine filled with explosives and an airplane full of fuel oil is way more dangerous than a smaller helicopter. So, if they're looking at these smaller platforms, it's because we forced them to look at these small platforms because we did approve security in the other areas, that's actually a success.

GIBSON: Jim Walsh, terrorism analyst at Harvard. Jim, thanks a lot, appreciate it.

WALSH: Thank you, John.

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