NSA: 'Over 50' Terror Plots Foiled by Data Dragnets Full list of foiled plots will be provided to lawmakers, but not publicly.

June 18, 2013 -- The director of the National Security Administration today told Congress that more than 50 potential terrorist attacks have been thwarted by two controversial programs tracking more than a billion phone calls and vast swaths of Internet data each day.

The attacks on would-be targets such as the New York Stock Exchange were prevented by caching telephone metadata and Internet information, including from millions of Americans since Sept. 11, 2001, Gen. Keith Alexander said during a hearing at the House Permanent Select Committee on Intelligence.

Alexander had been less specific in testimony last week when he said "dozens" of possible attacks were foiled.

He testified today: "In recent years, these programs, together with other intelligence, have protected the U.S and our allies from terrorist threats across the globe to include helping prevent the potential terrorist events over 50 times since 9/11."

He appeared in a rare public hearing of the House Intelligence Committee with officials from the FBI and Justice Department to discuss the phone and Internet programs that were disclosed in June by former NSA contractor Edward Snowden in the British Guardian newspaper and also The Washington Post.

Edward Snowden Says "I'm No Chinese Spy"

Lawmakers had previously disclosed that about a dozen attacks were believed to have been thwarted as a result of the programs.

Alexander said the full list of thwarted attacks will be provided to members of the House Intelligence committee Wednesday, but the intelligence community has decided to release only two of those events publicly.

"If we give all those out, we give all the secrets of how we're tracking down the terrorists as a community," Alexander said. "And we can't do that."

But he and other intelligence officials have pointed specifically to the case of Najibullah Zazi, the Afghan-born man who pleaded guilty in 2012 to plotting a terror attack against the New York City subway system. He is awaiting sentencing.

More About Would-Be Bomber Najibullah Zazi

FBI Deputy Director Sean Joyce testified today that "In the fall of 2009, NSA, using 702 authority [granted to intercept communication], intercepted an email from a terrorist located in Pakistan. That individual was talking with the individual located inside the United States talking about perfecting a recipe for explosives.

"Through legal process, that individual was identified as Najibullah Zazi. He was located in Denver, Colorado. The FBI followed him to New York City. Later, we executed search warrants with the New York Joint Terrorism Task Force and NYPD and found bomb- making components and backpacks. Zazi later confessed to a plot to bomb the New York subway system with backpacks," Joyce said.

The plot was previously disclosed.

It has been argued by Snowden and others that the coded email message that foiled Zazi's plot could have been uncovered without the controversial PRISM electronic surveillance program, which apparently collects data from everyone for later dissection and not just suspected terrorists.

Snowden, who has said he has more information to leak, accused administration officials and members of Congress in an online chat with The Guardian Monday of exaggerating claims about the success of the data collection programs in arresting terrorists, specifically New York subway bomb plotter Najibullah Zazi.

The FBI's Joyce also said the NSA was able to provide the FBI with a previously unknown telephone number of Adis Medunjanin [who was convicted along with Zazi], which helped disrupt "the first core al Qaida plot since 9/11, directed from Pakistan."

In today's newest revelation, he also said the NSA monitored a known extremist in Yemen, who was in contact with an individual in the United States, Khalid Ouazzan, which led to detection of "a nascent plot to bomb the New York Stock Exchange."

Joyce also cited the case of David Headley, a U.S. citizen living in Chicago later convicted for his involvement in the 2008 Mumbai attacks in which more than 160 people died. Joyce said the NSA, through 702 coverage of an al Qaida-affiliated terrorist, found that Headley was working on a plot to bomb a Danish newspaper office that had published cartoon depictions of the prophet Muhammad.

"Lastly, the FBI had opened an investigation shortly after 9/11," Joyce said, without further identifying specifics of the potential attack. "We did not have enough information nor did we find links to terrorism, so we shortly thereafter closed the investigation.

"However, the NSA, using the business record FISA [Foreign Intelligence Surveillance Act], tipped us off that this individual had indirect contacts with a known terrorist overseas. We were able to reopen this investigation, identify additional individuals through a legal process and were able to disrupt this terrorist activity."

The House Intelligence hearing is ongoing. Check back for updates.