Alexander said at least ten of the attacks were set to take place in the United States. NSA: PRISM stopped NYSE attack

Recently leaked communication surveillance programs have helped thwart more than 50 “potential terrorist events” around the world since the Sept. 11 attacks, National Security Agency Director Keith Alexander said Tuesday.

Alexander said at least 10 of the attacks were set to take place in the United States, suggesting that most of the terrorism disrupted by the program had been set to occur abroad.


The NSA also disclosed that counterterrorism officials targeted fewer than 300 phone numbers or other “identifiers” last year in the massive call-tracking database secretly assembled by the U.S. government.

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Alexander said the programs were subject to “extraordinary oversight.”

”This isn’t some rogue operation that a group of guys up at NSA are running,” the spy agency’s chief added.

The data on use of the call-tracking data came in a fact sheet released to reporters in connection with a public House Intelligence Committee hearing exploring the recently leaked telephone data mining program and another surveillance effort focused on Web traffic generated by foreigners.

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Alexander said 90 percent of the potential terrorist incidents were disrupted by the Web traffic program known as PRISM. He was less clear about how many incidents the call-tracking effort had helped to avert.

Deputy FBI Director Sean Joyce said the Web traffic program had contributed to arrests averting a plot to bomb the New York Stock Exchange that resulted in criminal charges in 2008.

Joyce also indicated that the PRISM program was essential to disrupting a plot to bomb the New York City subways in 2009. “Without the [Section] 702 tool, we would not have identified Najibullah Zazi,” Joyce said.

However, President Barack Obama acknowledged in an interview aired Monday that it is impossible to know whether the subway plot might have been foiled by other methods.

”We might have caught him some other way. We might have disrupted it because a New York cop saw he was suspicious. Maybe he turned out to be incompetent and the bomb didn’t go off. But at the margins we are increasing our chances of preventing a catastrophe like that through these programs,” Obama told Charlie Rose on PBS.

At the hearing, Alexander detailed the scope and safeguards of the programs, while Deputy Attorney General James Cole laid out the legal basis for the surveillance.

“This is not a program that’s off the books, that’s been hidden away,” Cole said of the call-tracking program, which was classified “top secret” prior to recent leaks. He noted that the Patriot Act provision found to authorize it has been twice reauthorized by Congress.

“All of us in the national security [community] are constantly trying to balance protecting public safety with protecting people’s civil liberties,” Cole said.

NSA Deputy Director Chris Inglis said a very limited number of individuals are authorized to access the call-tracking database.

“Only 20 analysts at NSA and their two managers, for a total of 22 people, are authorized to approve numbers that may be used to query this database,” Inglis said.

Inglis said judges on the Foreign Intelligence Surveillance Court have imposed strict limits on the ways the call information can be used.

“The court has determined that there’s a very narrow purpose for this use,” the NSA official said. “It can’t be used to do anything other than terrorism.”

Several officials said the judges on the largely-secret court rigorously examine applications for surveillance and often insist on changes, even though the court almost always approves them in the end.

“There is, from my perspective, no rubber stamp,” Alexander said.

“They will almost invariably come back with questions, concerns, problems that they see,” Director of National Intelligence General Counsel Robert Litt said. He described “rather extensive and serious judicial oversight of this process.”

“They push back a lot,” Cole added. “They have to be satisfied.”

At the outset of the hearing, House Intelligence Committee Chairman Mike Rogers (R-Mich.) strongly defended the programs and decried what he called “fragmentary and distorted illegal disclosures” leaks that bred misinformation about the surveillance efforts.

“People at the NSA in particular have heard a constant public drumbeat about a laundry list of nefarious things they have been alleged to have been doing to spy on Americans….All of them wrong,” the chairman said.

And he warned that misinformation could erode public faith in the programs.

“That trust can start to wane when faced with inaccuracies, half-truths and outright lies about how the intelligence aspects [of these operations] are being run,” the chairman added.

However, Rep. Jan Schakowsky (D-Ill.) suggested some of the loss of public trust derived from the sudden disclosure of the far-reaching surveillance programs that have alarmed some Americans.

“I would argue that this conversation that we’re having now could have happened” earlier, she said. “The effort that has [been made] to convince the American public of the necessity of this program, I think, would suggest that we would have been better off having a discussion of the rigorous oversight, the legal framework, etc., up front.”

Schakowsky also said that given the numbers of people who had access to the information about the programs, she could not understand why anyone could have expected the efforts to remain secret for years.

Only one lawmaker on the panel, Rep. Jim Hines (D-Conn.), indicated that he views the surveillance as a serious intrusion on privacy.

Himes said he was troubled by “the breadth and the scope of the information collection,” which sweeps up data on nearly every telephone call made in the United States.

“The controls that you’ve laid out for us notwithstanding — that’s, I think, new for this country,” Himes said. “Where do we draw the lines?…Where is the limit as to what you can keep in the tank?”

Cole said the scope of the data collected was not the important point. “I think the real issue is what it can be used for,” he said. ”If you’re looking for a needle in a haystack, you have to get the haystack first.”

Alexander said that the system for querying the data is “100 percent auditable,” so that any rogue official who might try to use it for an improper purpose “will be caught.”

Under questioning by Rep. Mike Pompeo (R-Kan.), Alexander did put to rest rumors that the call-tracking database contains information on where callers are, perhaps from cell phone towers or signal strength of calls.

“We don’t have that,” Alexander said. The only geographic information is the area code associated with the numbers, the NSA chief said.

Himes asked the administration officials to specify how many terrorist attacks would have taken place “but for” the call-tracking program.

Alexander said the “vast majority” of “just over 10” thwarted domestic attacks involved use of the massive call database.

But Joyce said there was no way to know for certain, as officials connected the dots, which particular pieces of data were critical and which simply helped.

“I think you asked an impossible to question, to say how important each dot was,” Joyce said.”Every tool is essential and vital.”

Rogers told reporters after the hearing that even the modest number of terrorist attacks disrupted by use of the call-records database could have had devastating consequences and justified the collection of the information.

“If you stop one Boston-style attack or a 9/11 attacks or you stop one case as we did with the stock exchange attack…as we saw recently you’re not going to stop every single one, but if you can stop ten of the magnitude of that, that’s huge. I would not get caught up on the number of plots stopped,” the chairman said.

Some have suggested could be reorganized to require telecom companies to keep the data rather than the government. Rogers said he was open to changes to the program, but that the current arrangement offers the advantage of speed in following up terror-related leads.

“If you need it, you need it now — if you’re going to stop an attack. Technology the way it is has not necessarily allowed the intelligence community [to access this data] in any other format than what we find it,” the chairman said. “The other ways and the other suggestions — technology doesn’t allow for a quick turnaround time.”

The hearing also produced extensive discussion about the impact of the leaks carried out by former NSA contractor Edward Snowden.

“It was irreversible and significant damage to our nation,” Alexander said.

“It is at times like these when our enemies within become almost as damaging as the enemies on the outside. It is critically important to protect sources and methods so we aren’t giving the enemy our playbook,” Rogers said.

Asked by a lawmaker about what Snowden could expect next, the FBI’s Joyce offered a pithy one-word answer: “Justice.”

Several panel members also expressed deep concern about how safeguards that should have prevented such widespread leaks apparently broke down.

“We must figure out how this could have happened,” said the intelligence panel’s ranking Democrat, Rep. Dutch Ruppersberger of Maryland. “How was this 29-year-old system administrator able to access such highly classified information about such highly sensitive matters? And how was he able to download it and remove it from his workplace undetected?”

Alexander said system administrators like Snowden have traditionally had wide access to networks and data, but officials are preparing a “two-person rule” that would make it more difficult for a single person to collect a vast number of top-secret documents. “We are going to implement that,” he said. He also indicated new safeguards on removable media, like memory sticks, are in the works.

Inglis said such a “two-person rule” already applies to NSA officials generating queries to the agencies databases, including the recently revealed surveillance programs.