WASHINGTON — Operating under secret court orders, the National Security Agency has access to a large segment of U.S. and global Internet traffic, allowing the giant spy agency to intercept specific information for counter-terrorism and foreign intelligence purposes, according to current and former intelligence officials.
News leaks this week revealed a highly classified NSA program code-named PRISM that allows it to mine data from domestic Internet and social media companies under certain circumstances. But PRISM is part of a much larger evolving effort by the intelligence agency to scoop up as much Internet traffic as possible, the officials said.
Most Internet data moves through fiber-optic cables in the United States, and the NSA physically intercepts much of it through equipment installed at telecommunications facilities, or from undersea cables.
But two trends have forced the NSA to adapt in recent years. Google and other major U.S.-based Internet providers have built computer server farms and data centers abroad. In addition, an increasing amount of digital traffic, including Google's Gmail service, is encrypted to ensure privacy and to thwart cyber-theft.
The 6-year-old PRISM program appears to be a response to those developments. The agency can access emails, video and other data directly from the companies, U.S. officials said. It's far simpler than tapping computer lines overseas or trying to decrypt emails.
It's "the easy way," a former senior NSA official said. "It's also the complete way. You don't have to worry about missing anything."
U.S. officials denied Friday that the NSA had direct access to Internet company servers or their data streams, challenging published reports on the PRISM program. The officials said the NSA needs a surveillance court order to obtain bulk data, and must notify the companies.
The NSA was chartered to collect foreign intelligence. But as a general matter, surveillance on the Internet makes it difficult to cull Americans from the data stream and only focus on foreigners.
"You can set up a wiretap between Minsk and Pinsk and get Americans," said Stewart Baker, a former NSA general counsel who was not briefed on the PRISM program.
The NSA reportedly seeks to "minimize," or disregard, data on U.S. citizens that it is not authorized to collect. However, the agency has wide leeway under laws passed since Sept. 11, 2001, to target individual Americans if it can convince the Foreign Intelligence Surveillance Court that there is probable cause to believe the individual has terrorist links.
Under the court orders, Internet companies turn over data that meet so-called validated selectors chosen by the intelligence community. Those could be phone numbers, email addresses or other data that suggest a terrorist tie-in or foreign espionage.
A similar legal structure is used for the giant archive of telephone company records that the NSA has assembled since at least 2007. The trove includes toll records for every local call in the United States, as well as those to or from overseas numbers. But officials said a separate court order is required to utilize the vast database in any given investigation.
If the validated selectors show, for example, that an American is in contact with militants in Pakistan, the NSA could then use a warrant to obtain the American's emails and other digital communications as well as permission to eavesdrop on phone calls.
"If it hits on that person's communication, and I have been in communication with that person, then it's likely that my phone number or email address will be pulled out," the former official said. At some point, the FBI would go back to the surveillance court and seek a more specific warrant.
On Friday, two Democrats who serve on the Senate intelligence committee, Mark Udall of Colorado and Ron Wyden of Oregon, disputed claims by Obama administration officials that collecting Americans' phone records had helped thwart terrorist attacks.
"After years of review, we believe statements that this very broad Patriot Act collection has been a critical tool in protecting the nation do not appear to hold up under close scrutiny," they said in a joint statement.
Times staff writer Chris O'Brien in San Francisco contributed to this report.