MICHEL MARTIN, HOST:

Continuing with our international focus, there's another story that got our attention. It comes from The New York Times, which reports that seven years ago, the Chinese government began systematically destroying the CIA spy network across the country by killing or imprisoning more than a dozen CIA sources. The Times says it was one of the worst intelligence breaches in modern history.

But there are still many questions about how it happened and how much damage was done. One of the reporters on the story is Mark Mazzetti. He covers national security for The New York Times. We reached him via Skype in Washington, D.C., where he's based.

Mark Mazzetti, thank you so much for speaking with us.

MARK MAZZETTI: Thanks for having me on.

MARTIN: Just briefly tell us what you found out.

MAZZETTI: Between 2010 and 2012, the Chinese basically dismantled the CIA's network of informants inside the country. People were captured or killed. More than a dozen of the CIA informants were killed and executed. One was even, we're told, shot in a sort of courtyard of a government building in front of his colleagues as a sort of message to - for those who might be thinking about spying for the CIA.

They didn't, ultimately, determine what had happened, how this breach had occurred. There were some who thought there was a mole in the CIA giving the Chinese the sources or some thought that there was a technical problem, that the Chinese had hacked into the encrypted system the CIA uses to talk to its informants.

MARTIN: Has there been any response to this report from any country?

MAZZETTI: Not so far. We reported this over several weeks. And frankly, we were surprised that something like this had sort of remained a secret for so long. And it's still early in terms of any kind of responses. And sometimes, when you're dealing with - you know, talking about intelligence stories and spy networks, etc., there may never be any public comment by the countries involved.

MARTIN: Do you have a sense of the consequence of this occurring? What are your sources saying?

MAZZETTI: There's no question that this is a huge setback for the CIA in terms of understanding what is going on in China, being able to understand how decisions are made in Beijing, who might be disillusioned with the government. These are the type of things that the CIA would try to - the secrets it would try to steal from China. So when you lose most of your source network or a large part of your source network, you're going to be blind largely in that country. And these things take years to rebuild.

We think that they have taken steps to rebuild the network, but this is not something that can be done overnight. So China is a big important country that is really a focus of American intelligence gathering. And when something like this happens, you're going to lose visibility. And that, you know, has national security implications.

MARTIN: To the degree that you can answer this question - I mean, in your reporting you say that this effort to dismantle the spy network through these rather brutal means concluded around the end of 2012. So how does the U.S. gather intelligence now?

MAZZETTI: They are trying to get back more sources. They are trying to better find ways to do intelligence collection electronically through intercepted communications, eavesdropping, that type of thing. But human sources are always the best. You know, we don't think necessarily they lost every single source. So they - some remained. They were able to mitigate the damage after a couple of years.

However, as I said, what we think was that they had particularly good information for a period of time. Their sources were, in fact, very well-connected. And when you lose those, you know, you are going to have difficulty possibly for years.

MARTIN: That was Mark Mazzetti. He was the lead reporter on the story that we've just been talking about, the Chinese government dismantling the CIA's spying operations in the country. He covers national security at The New York Times, and he was with us via Skype.

Mark Mazzetti, thank you so much for speaking with us.

MAZZETTI: Thank you. Transcript provided by NPR, Copyright NPR.