MELISSA BLOCK, host:

So what new information led the nation's 16 intelligence agencies to reverse their conclusion on Iran's nuclear program? Mark Mazzetti wrote about that today as national security correspondent for the New York Times. He says for one thing, the intelligence community widened its net, turning to multiple varied sources, and compiling a more accurate picture of Iran's nuclear program.

Mr. MARK MAZZETTI (Correspondent, The New York Times): We believe it was a combination of some human sources combined with some electronic intercepts that they were then able to piece together. I think if they learned anything from the Iraq episode, it was not to rely too much on one even human source who could be lying.

BLOCK: The communication intercepts that you mentioned - according to some reports, they were conversations that referred to the program having been stopped in 2003, which, of course, raises the question about how anyone would know that that's not disinformation. How do you judge an intercept to know whether what the person is saying is actually true or designed to steer you off track?

Mr. MAZZETTI: That's the first thing that they wonder about, and there's an entire division of the CIA doing counterintelligence to try to assess whether adversaries are feeding the U.S. information to throw us off the trail. This - senior intelligence officials have said that a lot of their time this summer was spent trying to figure out whether this great information that they got this year was trying to throw the United States off. They ultimately determined that all of the information in totality was legit.

BLOCK: It also seems that what's going on here was not just new information coming in from different sources, but also a change in how the intelligence community was analyzing that information - a real culture change.

Mr. MAZZETTI: That's right. And about a year, a year and a half ago, the senior analyst in the intelligence community, basically, put in some new procedures to say what happened with the 2002 Iraq NIE will never happen again. What it is is, in many ways, coming - being upfront about what you don't know, allowing alternate viewpoints. What they used to do was they try to get a consensus and then if anyone dissented, they stuck a dissent down at the bottom of the page.

What they're doing now is they're putting alternate views right upfront and they're saying, you know, you decide for yourself. So they're trying to encourage these different views. What's interesting really about this product is that they came out with remarkably bold statements saying, we have high confidence that Iran stops this program in 2003. So they're in a way going out on a limb, saying that we are very, very sure about this.

BLOCK: You've written about the use now of Red Team. So explain what a Red Team is.

Mr. MAZZETTI: A Red Team is basically in layman's terms a devil's advocate, setting up a team to challenge the views of the intelligence community, basically saying, well, what if it's this and what if it's that and, you know, try to poke holes in the prevailing wisdom. You know, that feeling is if they can survive this process and survive the test of these hypotheses, then maybe in the end, they'll be stronger.

BLOCK: How much of this do you think may have been a result of them going back to the very same information they had in 2005, with fresh eyes, with a new way of looking at the same stuff they had before?

Mr. MAZZETTI: That's right. And from what I can tell, they took this approach with this NIE to basically say, all right. Let's throw away our preconceived notions and see what we can come up with. They've got some new information - some, apparently, very good information that then allowed them to go back to earlier assessments and old information that they had kind of discarded, and then put those pieces together in new ways to create this new picture.

BLOCK: Mark, when you read through the NIE, you'll see terms used like high confidence, moderate confidence - these have very specific meanings, but to a layperson mean really not much at all. Can you explain what the distinctions are?

Mr. MAZZETTI: Well, and I think that they mean different things today than they may have a couple of years ago. As I said that there was a sort of a change in how they did the analysis. In many ways, it comes down to percentage. They can say to something with 80 or 90 percent confidence, they would then label high confidence. They are terms of art. They are - they admit very imprecise what is the boundary between moderate confidence and high confidence. I think it's very striking that they came out with high confidence in this assessment when they'd come out with high confidence in 2005 so they've really done a total reversal. They have sort of put their cards on the table and said, this is what we believe. And when you're talking about Iran, it's - they knew that this was going to feed right in to a high level international debate about Iran, into the middle of a presidential campaign, so they knew what they were doing.

BLOCK: Now that there's been this huge reversal, how do you explain what led to a 2005 assessment that has proved to be, apparently, completely wrong?

Mr. MAZZETTI: Well, it's not completely wrong. At least, there were some key parts that seemed to be wrong.

BLOCK: Right, right.

Mr. MAZZETTI: It is a little puzzling. I mean, the Iran NIE in 2005 came out two months after the big presidential commission chastised the intelligence community for getting it wrong about Iraq. By most accounts, the 2005 estimate was an update to an earlier assessment. They didn't do the hard scrub of sources of analysis that they did in this case. There were some people who were pretty wedded to this view that Iran was still continuing to build a nuclear weapon - determinable nuclear weapon - and they kind of went along with that prevailing view.

It really was - the 2005 estimate was really the last product under kind of the old regime. So since that time period, they have installed these new safeguards, not to say that - and they'll the first to admit that they're going to get a lot of things wrong, but they feel like they're at least prouder of what they're producing.

BLOCK: Mark Mazzetti, national security correspondent for the New York Times, thanks very much.

Mr. MAZZETTI: Thanks a lot. Transcript provided by NPR, Copyright NPR.

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