Despite bin Laden's death, terror threat remains

The head of al Qaeda in Yemen warned Wednesday that despite Osama bin Laden's death, the terror group is stronger than ever. In Washington , CBS Evening news anchor Katie Couric spoke with Homeland Security Secretary Janet Napolitano about the threat of retaliation.

Napolitano: One source of concern is what is called "the lone wolf." That is somebody who's in the United States, a United States citizen. He may have become radicalized by the internet to the point of violence. And says "in retaliation for the death of Osama bin Laden, I'm going to do X." And a sole actor, who's not in contact with anyone. That's very difficult to prevent.

Couric: There was a veritable treasure trove, of course, of information that was seized from the compound. What kinds of things have you gleaned about potential threats as a result?

Complete Coverage: The Killing of Osama bin Laden

Napolitano: Continued references to transportation, to aviation and to rail. And so, we're in contact with, say, Amtrak and other rail carriers across the country. And making sure that they are following their own safety procedures.

Couric: Did you increase security on trains across the country when you got word that they were potential targets?

Napolitano: We provided information to rail to see if they needed any additional resources. And I think that's the way we need to work. We need to be providing information, providing backup. We, of course, don't control. We control aviation, in a sense, much more than rail and transit. That's much more local in nature.

Couric: And have they, in response to this potential threat, increased security?

Napolitano: I haven't been in touch with any of them directly.

Couric: Some of the information that was seized, was there any evidence of sleeper cells operating in this country?

Napolitano: I don't want to talk about what was found necessarily in the compound. That's still being digested, translated, gone through. But I can say that we do operate under the premise that - be it a homegrown terrorist or a group - they may be actually operationally in touch with al Qaeda. We just operate under that assumption.

Napolitano gave CBS News a tour of her department's nerve center for transportation security. Located in a non-descript office complex near Dulles International Airport, information gathered at the center can determine whether the department issues a terrorism alert under a new system that replaced the color-coded threat levels established after 9/11.

Napolitano: We need to communicate really information to people so that if something is, comes in and it is specific and its credible, we can immediately issue an alarm.

Couric: What level are we at right now in the wake of Osama bin Laden's death?

Napolitano: The baseline has gone up. You know, when the color coded system was invented, the baseline was still, it was a pre-9/11 baseline. But terrorism threats continue to grow, they continue to evolve and so the actual baseline is elevated.

Couric: So the regular level these days is a heightened level?

Napolitano: That's another way to say it. Yes. We've elevated the base.