The recent revelations of the NSA’s surveillance programs have prompted much debate about whether the power granted to the intelligence community has been worth its potential for erosion of personal liberty.  Most of that debate has necessarily been academic, since the intel and law-enforcement agencies involved are loathe to share specifics on their counter-terrorism efforts, and what they do share cannot easily be corroborated.  One early defense of the program was that it stopped the Zazi plot against New York’s subway system, only to have later information contradict that claim.

Yesterday, the FBI’s assistant director told Congress that the programs stopped as many as 50 separate terrorist plots against the US, including one that targeted the core of America’s economy:

Top U.S. security officials revealed today that the government’s recently exposed surveillance programs led them to an al Qaeda cell that plotted, scouted, but ultimately abandoned a plan to bomb the Wall Street in 2008.

“We found through electronic surveillance that they were actually in the initial stages of plotting to bomb the New York Stock Exchange,” FBI Assistant Director Sean Joyce told the House Permanent Select Committee on Intelligence.

Joyce was testifying alongside high-level U.S. officials, including National Security Agency head Gen. Keith Alexander, before the House Intelligence Committee to defend the NSA’s practice of collecting vast amounts of telephone and internet usage data – programs revealed last week byformer NSA contractor Edward Snowden. Snowden, who is in hiding in Hong Kong after confessing to the leaks, called the reach of the programs “horrifying.” The U.S. officials who testified today claimed they helped put a stop to more than 50 terror plots in 20 countries – four of which were discussed publicly.

The NYSE plot, which had until today been unknown to the public, was centered around an auto parts dealer in Kansas City, Missouri, named Khalid Ouazzani, who pleaded guilty in 2010 for his role in a conspiracy to provide funding to al-Qaeda. At the time of his plea, the complex case against Ouazzani seemed to have little to do with the famous NYSE headquarters on Wall Street in Lower Manhattan, except for a vague reference in his plea agreement that said, “Over a period of years, [Ouazzani] and others discussed various ways they could support al Qaeda.”

The FBI now says Ouazzani was talking to an extremist in Yemen about a terror plot that would strike at the symbolic heart of America’s capitalist system – an attack on Wall Street.

Joyce also insisted that the unraveling of the Zazi plot was indeed dependent on NSA efforts, despite later claims to the contrary.  Those are the only two plots the FBI will discuss in public,  but NSA chief Keith Alexander will supply the House Intelligence Committee with a full list today:

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.

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.

In the end, we have to rely on our elected representatives to conduct oversight over these agencies and their activities.  If the House Intelligence Committee is just now finding out about the NSA’s surveillance and its victories, that’s an argument that the oversight has been lacking until now.  That much power may be needed to secure the nation from foreign attack, but that much power without effective oversight will eventually get abused — whether or not it already has.

We need to find out whether or not it has in the past, too.  USA Today reported this weekend that three other whistleblowers agree with leaker Edward Snowden that the NSA has crossed the line repeatedly, recapped by The Atlantic:

Thomas Drake, William Binney, and J. Kirk Wiebe each protested the NSA in their own rights. “For years, the three whistle-blowers had told anyone who would listen that the NSA collects huge swaths of communications data from U.S. citizens,” the newspaper reports. “They had spent decades in the top ranks of the agency, designing and managing the very data collection systems they say have been turned against Americans. When they became convinced that fundamental constitutional rights were being violated, they complained first to their superiors, then to federal investigators, congressional oversight committees and, finally, to the news media.”

In other words, they blew the whistle in the way Snowden’s critics suggest he should have done. Their method didn’t get through to the members of Congress who are saying, in the wake of the Snowden leak, that they had no idea what was going on. But they are nonetheless owed thanks.

And among them, they’ve now said all of the following:

• His disclosures did not cause grave damage to national security.

• What Snowden discovered is “material evidence of an institutional crime.”

• As a system administrator, Snowden “could go on the network or go into any file or any system and change it or add to it or whatever, just to make sure — because he would be responsible to get it back up and running if, in fact, it failed. So that meant he had access to go in and put anything. That’s why he said, I think, ‘I can even target the president or a judge.’ If he knew their phone numbers or attributes, he could insert them into the target list which would be distributed worldwide. And then it would be collected, yeah, that’s right. As a super-user, he could do that.”

• “The idea that we have robust checks and balances on this is a myth.”

• Congressional overseers “have no real way of seeing into what these agencies are doing. They are totally dependent on the agencies briefing them on programs, telling them what they are doing.”

• Lawmakers “don’t really don’t understand what the NSA does and how it operates. Even when they get briefings, they still don’t understand.”

• Asked what Edward Snowden should expect to happen to him, one of the men, William Binney, answered, “first tortured, then maybe even rendered and tortured and then incarcerated and then tried and incarcerated or even executed.” Interesting that this is what a whistleblower thinks the U.S. government will do to a citizen. The abuse of Bradley Manning worked.

• “There is no path for intelligence-community whistle-blowers who know wrong is being done. There is none. It’s a toss of the coin, and the odds are you are going to be hammered.”

For that, Congress has to accept a good deal of responsibility.