Privacy advocates expressed outrage Thursday over revelations that the National Security Agency has been collecting telephone records of virtually every phone call made in the United States for seven years, but the Obama administration and a bipartisan group of lawmakers defended the program as both legal and necessary.
Top House and Senate lawmakers who oversee the NSA, which has its headquarters at Fort Meade, said they had been briefed regularly on the domestic surveillance operation and dismissed concerns that the collection of phone logs was overly intrusive.
Without offering details, two lawmakers, including Rep. C.A. Dutch Ruppersberger of Baltimore County, said the program thwarted a planned domestic terrorist attack several years ago. Ruppersberger, the top-ranking Democrat on the House Intelligence Committee, was one of the lawmakers routinely briefed on the program.
"Terrorists will come after us if they can, and the only thing we have to deter this is good intelligence," said Sen. Dianne Feinstein of California, the Democratic chairwoman of the Senate Intelligence Committee.
"It's called protecting America," she said.
The Republican chairman of the House Intelligence Committee, Rep. Mike Rogers of Michigan, also defended the program, arguing that "nothing happens here without a court approval."
But the bipartisan defense of the secret program was unlikely to quiet questions about the extent of the agency's data collection. The revelations immediately reignited a broader debate — waged forcefully in the U.S. since the 2001 attacks — over how the government balances anti-terrorism efforts against an individual's right to privacy.
A court order published Wednesday by Britain's Guardian newspaper documented that the NSA relied on the 2001 Patriot Act to request the records of one phone company, Verizon. But officials made clear Thursday that the program was of long standing and strongly suggested that similar directives covered most if not all phone carriers.
The NSA collected the time, date and duration of calls as well the phone numbers involved for at least seven years, officials said. The agency stores the data but cannot use it, several officials said, without first obtaining a warrant from a court that meets in secret. Officials also stressed that the data does not include the contents of calls.
Mark Rumold, an attorney for the Electronic Frontier Foundation, a digital privacy watchdog group, said the order "targets more people than has ever been issued before, that we have known about publicly, in the history of the United States."
"There has been a significant amount of debate about the subpoenaing of AP reporters' phone records," Rumold said. "This is that on steroids. It's everyone."
White House spokesman Josh Earnest described the program as "a critical tool in protecting the nation." He also said that "the president welcomes a discussion of the trade-offs between security and civil liberties."
But Sen. Barbara A. Mikulski, a member of the Senate Intelligence Committee, called on members of the Obama administration to conduct a classified hearing for the entire Senate to explain how the program works.
Mikulski said the argument by the Obama administration that lawmakers had already been briefed "drives us up the wall."
" 'Fully briefed' doesn't mean we know what's going on," the Maryland Democrat said during an unrelated hearing on Capitol Hill. "We've got to know what's going on, and there are appropriate questions to ask."
Mikulski later said in an interview that she wants to know, "Is it constitutional? Is it legal? Is it desirable?" Frequently an ardent defender of the NSA, Mikulski did not directly answer whether she had been briefed on the program.
Patrick Toomey, a fellow with the ACLU National Security Project, said the group has long had concerns the government was collecting such data but was never able to confirm it. Those concerns were raised as Congress debated the 2001 Patriot Act, the law that officials said permits the data collection.
Congress reauthorized the law in 2011.
"We hope that the public becomes more aware of the ways in which the government is using the Patriot Act to monitor American phone calls on a wide, wide level," Toomey said. "We also hope that this is really a wake-up call for Congress."
Senior members of both parties in Congress defended the program in uncompromising terms, arguing that legal safeguards had been put in place in recent years and that the surveillance had succeeded in foiling terrorist plots.
"If you're calling your grandmother. I don't want people to know that — and they don't," said Ruppersberger, whose district includes the National Security Agency. The program is intended "to protect Americans, especially from outside terrorists."
Rogers argued that the data is rarely used.
"The number of queries into this information is a fraction of a fraction of a fraction of one percent — it's infinitesimal," he said.
But Rogers could not say precisely how often the data had been queried because that information is classified, he said. For the same reason, neither Rogers nor Ruppersberger was able to provide any details about the terrorist attack they said had been thwarted by the program.
A Verizon spokesman did not return a request for comment.
Separately, The Washington Post reported Thursday that the NSA and FBI are tapping directly into the central servers of nine leading Internet companies in the U.S., extracting audio, video, photographs, emails, documents and connection logs that enable analysts to track a person's movements and contacts over time.
The highly secretive NSA, whose steel-and-glass headquarters off Route 32 are fenced off from the rest of Fort Meade, collects and processes intelligence gathered from telephone calls, Internet activity and other electronic communications.
The agency, which is part of the Department of Defense, has faced periodic criticism since the attacks of Sept. 11, 2001, over its interception of communications involving U.S. citizens.
In 2009, Congress investigated what Ruppersberger said at the time was a "serious" failure to comply with legal limits on its domestic eavesdropping activities. An internal review by the Justice Department and the NSA found that the agency's monitoring program had exceeded limits set by Congress the year before to safeguard citizen privacy.
In 2008, The Wall Street Journal reported that the NSA was monitoring vast quantities of domestic communications and records, such as emails, phone calls, Internet searches, credit card transactions and travel records.
Mikulski, along with all other members of the Senate but two, voted for the original Patriot Act in 2001. Cardin joined a majority of Democrats to support the legislation in the House. Since then, both lawmakers have supported additional limitations on the law.
Cardin, emerging from a briefing on the issue Thursday, said he was continuing to gather information but that he supported the broad framework of the program with the legal protections he said are in place.
"I'm not opposed to giving this tool to the government, but it's got to be justified," he said. "It's a balance. We have a responsibility…to make sure that this tool is being used properly."
Tribune Newspapers' Washington bureau contributed to this article.