NSA chief says spy programs helped stop more than 50 terror plots since 911

WASHINGTON (CNN) -- Plots to bomb the New York subway system and the New York Stock Exchange were among more than 50 stopped by secret surveillance programs, the director of the National Security Agency and other officials disclosed Tuesday.

The programs also helped stop a plan to attack the office of a Danish newspaper that came under heat for publishing a cartoon of the Prophet Mohammed in 2006, according to Sean Joyce, the deputy director of the FBI.

The disclosures by Joyce and NSA Director Gen. Keith Alexander came before a House Intelligence Committee hearing in which officials said they would declassify information on the thwarted plots.

Panel Chairman Rep. Mike Rogers welcomed Alexander's testimony on the benefits of the secret programs.

"I think you have struck the right balance between protecting sources and methods, and maintaining the public's trust, by providing more examples of how these authorities have helped disrupt terrorist plots and connections," Rogers, a Michigan Republican, said in his opening statement.

Last week, Alexander said the secret surveillance programs revealed in leaks of classified documents helped foil dozens of terror plots, but he offered no specific details.

At the urging of the leaders of congressional intelligence committees, he looked into declassifying information on some cases to provide a stronger public defense of the programs that critics have called government overreach.

There is a debate within the intelligence community about what can be revealed to prove the programs work, versus what should stay classified for fear of burning sources and methods.

President Barack Obama defended the secret programs in an interview with Charlie Rose broadcast Monday night, but he said the situation requires a national debate on the balance between security and privacy rights.

Gen. Keith Alexander courtesy wiki media