WASHINGTON — After weeks of mounting controversy and doubts in Congress, the Obama administration made its most detailed effort yet to reassure the public about the National Security Agency's massive collection of Americans' telephone records, releasing previously classified documents in an effort to save a program that appears increasingly endangered.
But the documents, which included a secret order from the Foreign Intelligence Surveillance Court that was once so highly classified that only those with a "need to know" could see it, appeared to do little to quiet the calls in Congress to rein in the NSA's authority. Officials testifying to a Senate panel ran into skeptical questions from members of both parties.
"It's been far too difficult to get a straight answer about the effectiveness" of the program, said Senate Judiciary Committee Chairman Patrick J. Leahy (D-Vt.). "I think the patience of the American people is beginning to wear thin, but what has to be of more concern in a democracy is the trust of the American people is wearing thin."
The newly declassified documents spelled out both the scope of the program and the safeguards that administration officials say protect the privacy of Americans. The NSA keeps five years' worth of records covering nearly all telephone calls in the United States, showing which phone numbers were connected to which other numbers and when.
Set against that massive pile of data are restrictions designed to prevent abuses. The court order authorizes only a small number of analysts and supervisors at the NSA to access the database for the limited purpose of looking for numbers that were contacted by phone numbers linked to terrorism.
Only 22 people are authorized to work with the data, according to Sen. Dianne Feinstein (D-Calif.), who chairs the Senate Intelligence Committee, although agency technicians can also access the database for more limited purposes.
Fewer than 300 terrorist-linked numbers were used as the starting points for searches of the database in 2012, officials said. Based on the results of those searches, NSA provided 12 reports to the FBI, tipping agents to 500 suspicious U.S. numbers, NSA Deputy Director John "Chris" Inglis said at a hearing of the Senate Judiciary Committee.
The release of that information came after weeks of intense debate within the administration and the intelligence agencies that began when former NSA contractor Edward Snowden disclosed numerous documents about the agency's activities. Some national security officials resisted declassifying the information, arguing that publicizing any aspect of the NSA's work could potentially tip off terrorists about the methods the agency uses to track them.
Yet even as officials talked more openly than before about the program's details, the disclosures came too late for many senators.
"We have a lot of good information out there that helps the American public understand these programs," said Sen. Sheldon Whitehouse (D-R.I.), "but it all came out late. It all came out in response to a leaker. There was no organized plan for how we rationally declassify this so that the American people can participate in the debate."
Others remained unconvinced that the benefits of the database outweigh the costs to Americans' privacy.
Asked during the hearing how many terrorism cases were cracked using U.S. phone records, Inglis said that a dozen domestic terrorism investigations had made use of the telephone records. But he could cite only one case that would not have been discovered but for the database: a group of men from San Diego who sent $8,500 to Al Qaeda-linked militants in Somalia.
One of the defendants in that case was discovered because his number had been called by a phone number in Somalia known to have been used by a terrorist group, Inglis said.
Leahy questioned whether the small number of cases justified the intrusion on Americans' privacy that the database represents.
"We could have more security if we strip-searched everybody that came into every building in America," Leahy said. "We'd have more security if we close our borders completely to everybody … if we put a wiretap on everybody's cellphone in America, if we search everybody's home.
"But there are certain areas of our own privacy that we Americans expect, and at some point, you have to know where the balance is," he said.
Even steadfast defenders of the NSA's activities conceded that some changes would be necessary.
"I believe, based on what I have seen — and I read intelligence regularly — that we would place this nation in jeopardy if we eliminated" the NSA's ability to collect telephone records and to gather information about Internet usage by foreign intelligence targets, Feinstein said. But, she added, the intelligence committee is considering proposals to change the programs, including providing the public with more data about how often phone numbers in the database are searched and reducing the length of time the government can keep the data to three years from the current five.
At a meeting with Senate Democrats, President Obama spoke about the NSA's activities. He told Sen. Richard J. Durbin (D-Ill.) that he was "open" to the idea of changing the way the foreign intelligence court works to provide "more transparency and a real court proceeding," Durbin said.
Some judges who have sat on the court have suggested that the judges be given the authority to appoint a public advocate to argue against the government's requests in some cases. Currently, only government lawyers appear before the court.
Other lawmakers are proposing that Congress require the phone companies, rather than NSA, to store the telephone data. The government could then query it as needed as it currently does, but it would not have custody of everyone's telephone records. The government would have to pay the companies to store the massive amounts of data.
Inglis said NSA is open to that idea, as long as the data are standardized.
But Stewart Baker, a former NSA lawyer, told the committee of problems he sees with that approach.
"Who's going to search it? Is the phone company going to search it?" he asked. "Are we going to ask China Mobile to do searches for national security targets on the data that they're storing? Or are we going to give access to the servers on the part of the government?"
In addition to the order from the secret court, the administration also released two letters to Congress, from 2009 and 2011, which explained that the government was using the Patriot Act and other laws to justify bulk collection of U.S. phone records. Release of those documents was designed to make clear that members of Congress had every chance to be fully informed about the program before they twice voted overwhelmingly to extend it.
As the debate over the collection of domestic telephone records intensified, Britain's Guardian newspaper published another disclosure from Snowden, involving the collection of intelligence outside the U.S. Those documents showed how NSA analysts can search databases of intercepted Internet traffic for foreign intelligence.
The bulk of NSA surveillance involves foreign targets. The government's legal authority to eavesdrop on people outside the U.S. — or non-Americans inside the country — is far greater than its powers regarding U.S. citizens because the Constitution does not protect foreigners.
The documents published by the Guardian showed how NSA analysts can use a program called XKeyscore to search through vast databases of intercepted Internet communications to find email, chats or browsing history of a specific person.
The NSA claimed in the documents, which had been used as training material, that by 2008, 300 terrorists had been captured using intelligence from XKeyscore.
The Guardian's story said the new documents "shed light" on Snowden's claim that "I, sitting at my desk," could "wiretap anyone, from you or your accountant, to a federal judge or even the president, if I had a personal email."
In fact, however, the system described in the story only allows analysts to look at already-collected data, mainly on foreigners, not to eavesdrop on a new subject in real time, former NSA officials said.
If an analyst tried to use the system to query a U.S. email address or phone number, "they might get some sort of alert back saying, 'Hey, that doesn't jibe,' and then humans would review all of it," said a former veteran NSA operator. "So to say that you can sit there and look at the president is ridiculous."
The forms that analysts have to fill out to query the database "leave a pretty thorough audit trail," the former operator said.
Michael A. Memoli in the Washington bureau contributed to this report.
e former operator said.
Michael A. Memoli in the Washington bureau contributed to this report.