JUDY WOODRUFF: For the latest on all of this, we turn to Dina Temple-Raston. She's the counterterrorism correspondent for NPR.
Dina, thank you for being with us.
Tell us, just exactly what do authorities know?
DINA TEMPLE-RASTON, NPR: Well, actually, there's more that they don't know than what they know.
But there was a source in Pakistan that had suggested sort of a vague plot. The vague plot involved at least three operatives, perhaps one American, perhaps a car bomb, something to coincide with the 9/11 anniversary. And it also seems that it was something that they had started. And that's what intelligence officials are trying to figure out now. What does started mean?
Does that mean they have already dispatched people? Does that mean it was planned? Does that mean people are here? So, in your piece, you talked about how they were scrubbing for information. What they're trying to do is take the information that they have from this one source and see how it might sort of jibe with other things that they have been picking up over the last couple of months.
JUDY WOODRUFF: Now, why are they focusing, apparently, on subways and bridges and so forth?
DINA TEMPLE-RASTON: Well, I think when you talk about car bombs and you want to have the maximum amount of damage, this is one of the places that al-Qaida has continually said it wants to focus on, particularly public transportation, because you can get a photograph of it, and it disrupts life as usual.
I mean, if you were in New York today, I mean, the mayor took the subway because, frankly, if you were on the streets of New York today, you had a lot of trouble getting around. I have never seen New York this way. It almost looks like the attack has already happened.
I mean, there are police cars everywhere. There are barricades down Fifth Avenue. This has really been ramped up.
JUDY WOODRUFF: I did interview, as we mentioned in that piece, John Brennan, the president's counterterrorism adviser, a couple of days ago, and he said ever since they went through Osama bin Laden's material when they killed him, they have known that there was an interest in doing something on the anniversary of 9/11. So they have been looking for something, I gather.
DINA TEMPLE-RASTON: They have.
And the reporting that we have been doing at NPR, what's been really unusual is in the run-up to the -- to this anniversary, there has been very, very little evidence of chatter. It seemed like al-Qaida leaders had gone to ground because so many of them had either been captured or killed by drone attacks, and they just seemed like they were sort of huddled up.
So this particular intelligence intercept that they got kind of surprised them, because there had been silence for so long.
JUDY WOODRUFF: So they're still investigating; is that right?
DINA TEMPLE-RASTON: That's exactly right. Basically, what happens is they get this intercept or they get a piece of intelligence that seems strong, and this particular source apparently has been very helpful to them in the past in cooperating and corroborating other things that have happened.
So they put more stock in it. It's interesting, because it's different than the way that journalists work. When you have an unconfirmed report, that's basically someone is giving you a hint and you try and get a second source. It doesn't really work that way with intelligence. And the way it works with intelligence is, generally, it's whether you have faith in the source. It could be one source, but if you have a lot of faith in that source, that changes the way you react.
And, apparently, this particular source, the way they got this piece of information is something they have a lot of faith in.
JUDY WOODRUFF: But, Dina, at some point, if they don't get corroboration, how do they dial back the threat here?
DINA TEMPLE-RASTON: Well, that's a great question.
And the other problem is, as dribs and drabs of this story come out, in which they might be looking for three operatives in this country, there might be an American, there's a very good possibility that if that is in fact true -- and we don't know it is -- but if that is in fact true, that these people go to ground and wait until the U.S. is not on such high alert. And this is one of the big concerns the intelligence community has with this story coming out in dribs and drabs the way it is.
JUDY WOODRUFF: Well, I know you will continue to report and we will continue to follow.
Thank you, Dina Temple-Raston.
DINA TEMPLE-RASTON: You're very welcome. Nice to be here.