NSA chief testifies before Senate on spying program

WASHINGTON -- The director of the National Security Agency said Wednesday that once-secret surveillance disrupted dozens of terrorist attacks, explicitly describing for Congress how the programs worked in collecting Americans' phone records and tapping into their Internet activity.

Vigorously defending the programs, Gen. Keith Alexander said the public needs to know how the programs operate amid growing concerns that government efforts to secure the nation are encroaching on Americans' privacy and civil liberties.

"I do think it's important that we get this right, and I want the American people to know that we're trying to be transparent here, protect civil liberties and privacy but also the security of this country," Alexander told a Senate panel.

Alexander cited in particular the cases of Najibullah Zazi, an Afghan American who pleaded guilty to planning suicide attacks in New York subways, and Pakistani American David Headley, who conducted surveillance in support of the 2008 attacks in Mumbai, which killed more than 160 people.

In both instances, he said, the Internet data-mining program helped unravel the plots.

Alexander said he will provide additional information to the Senate Intelligence Committee in closed session Thursday and hopes to have as many details as possible within a week. He said he wants the information to be checked first by other agencies to ensure the details are correct.

But he also warned that disclosures about the secret programs have eroded agency capabilities and, as a result, U.S. allies and Americans won't be as safe as they were two weeks ago.

"Some of these are still going to be classified and should be, because if we tell the terrorists every way that we're going to track them, they will get through and Americans will die," he said.

Alexander said that he would rather be criticized by people who think he's hiding something "than jeopardize the security of this country."

On Tuesday, a phalanx of FBI, legal and intelligence officials briefed the entire House in an attempt to explain NSA programs that collect millions of Americans' phone and Internet records. Since they were revealed last week, the programs have provoked distrust in the Obama administration from around the world.

House members were told not to disclose information they heard in the briefing because it is classified. Several said they left with unanswered questions.

"People aren't satisfied," Rep. Tim Murphy (R-Pa.) said as he left the briefing. "More detail needs to come out."