AUDIE CORNISH, HOST:
It's been two years since former National Security Agency contractor Edward Snowden exposed the spy agency's massive collection of Americans' phone records, and it's been two days since President Obama signed a law ending that practice. Yesterday on this program, Senator Patrick Leahy warned the NSA is also deeply involved in collecting Internet data.
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PATRICK LEAHY: Nobody knows how much they're doing, and that's what should be frightening to Americans.
CORNISH: What we know today, thanks to a New York Times story based on newly released documents from Snowden, is that the NSA's warrantless surveillance of the Internet has actually expanded under the Obama administration. Joining me to talk about this latest Snowden revelation is NPR national security correspondent David Welna. Welcome to the studio, David.
DAVID WELNA, BYLINE: Hi, Audie.
CORNISH: So what is it that we know today about the NSA's Internet surveillance that most of us did not know about yesterday?
WELNA: Well, you know, thanks to those documents Snowden made available to the New York Times, we know that the NSA has expanded its Internet surveillance in the U.S. to track down people abroad who are trying to track - to hack into Americans' computers. This is a program that's really never been debated publicly, and it's being carried out under a law that Congress passed seven years ago. Today, when he was asked about this latest spying revelation, White House spokesman Josh Earnest pointed to what's known as Section 702 of that law.
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JOSH EARNEST: And Section 702 does provide authority to target non-U.S. persons reasonably believed to be located outside the United States in order to acquire foreign intelligence information under court oversight.
WELNA: And Ernest did not elaborate on what kind of court oversight there might be of this program.
CORNISH: Is this program fully legal?
WELNA: We simply don't know what its legal status is today because the documents describing it are more than two years old. At the time, there had been two secret memos from the Justice Department that were written in 2012. They gave the NSA a green light to monitor hacking activity tied to foreign powers. But those documents indicate the NSA found it hard to link some hackers to foreign powers, and the agency wanted to be able to pursue them without having to first show these suspects were foreign agents. It's not clear whether it's actually doing that right now.
CORNISH: This is all supposed to be targeting foreign Internet hackers then, right? I mean, could this have any impact on Internet users here in the U.S.?
WELNA: It could indeed. Hackers, by definition, are trying to break into other people's computer accounts and steal their information, so monitoring their activity means watching them poach on other people's Internet usage and private data. I talked with Jonathan Mayer, a computer security fellow at Stanford who's reviewed these latest Snowden documents. He says because of the way the surveillance law is written, the NSA can actually hang on to that hacked information.
JONATHAN MAYER: Even though Americans may in fact have been the victims of the online crime, their information nevertheless becomes eligible for the U.S. government to take advantage of it. It may seem like an odd legal result. The government's view is that that victim information is incidentally collected and therefore can be used for intelligence.
CORNISH: David, is there any idea how much of Americans' online data the NSA has gathered through this cyber security surveillance?
WELNA: It's really not clear, which is also the case for a lot of other details about this program. Certainly it's not the massive amount of data the NSA's been scooping up about when people make phone calls to where and how long they last. Because of the USA Freedom Act that the president just signed, that kind of bulk data collection is ending in six months. Law under which this Internet surveillance is being carried out, though, won't be up for a congressional review for another two years. By then, we might know a lot more about it than we do today.
CORNISH: That's NPR's David Welna talking with us about new Edward Snowden revelations. David, thank you.
WELNA: You're welcome. Transcript provided by NPR, Copyright NPR.