This is a partial transcript of "The Big Story With John Gibson," May 26, 2005, that has been edited for clarity.

ANDREW NAPOLITANO, GUEST HOST: In a simulated world set five years into the future, the threat of cyberterrorism (search) is on the front lines. And the CIA (search) is making sure it's ready, setting up a three-day exercise simulating an electronic assault on our government and on our economy — one that's on the same scale as the September 11th attacks.

Joining us now to talk about this is former CIA official Ron Marks. Today's big question, Ron: What could the terrorists target in a cyber attack?

RON MARKS, FORMER CIA OFFICIAL: Well, in this world that we live in right now, with so much of what we have on the Internet — everything from banking to our financial work to commercial enterprise — I mean, a lot of the supply chain now is hooked up over the Internet. These guys have ample opportunity to attack a system in a way that they wanted to attack us for a while.

Remember, the World Trade Center attacks were about the U.S. financial system, about hurting us as deeply as they could and as quickly as they could. And while they were able to do that with two airplanes there, you can also do that in a cyber attack. You can really foul up some systems very badly. So, the CIA's efforts in this direction should be applauded. It's something that should be done and they should be doing, frankly, more of it.

NAPOLITANO: All right. How do these games work and what does the CIA think and what is it planning for if the bad guys might actually attack us?

MARKS: Well, in the best of all possible worlds, these are the kinds of games where people are set up in A and B teams, where, in essence, you have someone who is defending the homeland and you have someone who's attacking the homeland.

In this case, what you're looking for is what the vulnerabilities are. You want people, smart people, who know how the system is set up at this point to think about how they would attack you. And hopefully you have your A team, which is trying to defend this, not only defending it well, but also learning from the attack. Remember, you've got a pool of information here now on the Internet that is available throughout the world.

Hackers working for the U.S. government have the same kind of information as hackers that are working for Al Qaeda (search). So, you really want to get inside of these guys' mind, try to figure out what kinds of areas they would attack, what types of systems they might be using, what types of software they might be using. This is important stuff. And to get inside of their minds, to be prepared for it, to harden our defenses, is exactly what they should be doing.

NAPOLITANO: Where are we most vulnerable, Ron?

MARKS: Oh, the financial system clearly — by the fact that the Internet is as open as it is.

I mean, we've all seen it here in the past few weeks, just people at the Bank of America and Wachovia up in New Jersey at this point giving information away. The Internet is a really wild frontier in a lot of ways. It's an open highway. It was meant to be that way. But, really, it's in the last few years I think people have come to realize how much that system can be abused. And certainly by people who are looking to hurt us, it can be very, very badly abused.

NAPOLITANO: We only have a few seconds left.

Would part of these games involve us going on the offensive in a cyber attack against the bad guys before they get to us?

MARKS: You bet. You bet.

This is not just about defense. This is about offense. This is about getting inside of their heads, figuring how out how they're doing things and then proceeding to disrupt and attack them as well.

NAPOLITANO: Ron Marks, thanks very much.

MARKS: You're welcome.

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