The National Security Agency eavesdrops on communications all over the world. For a few years, the NSA was actually listening to Osama bin Laden's satellite phone calls. But even that wasn't enough to tip off U.S. intelligence to the 9/11 plot or to earlier attacks on the USS Cole and two American embassies in Africa. Bin Laden probably didn't realize it, but he was mounting these operations just as NSA was going through the worst crisis in its 50-year history. In fact, in the very same month two of the 9/11 hijackers entered the U.S., the supercomputers NSA relies on to sort through billions of phone calls, faxes, e-mails and radio transmissions crashed.
In January 2000, General Mike Hayden, the Director of NSA, got a phone call at home from the agency's watch officer telling him there'd been a national security meltdown.
As much of the East Coast dug out from a surprise snowstorm, Hayden went on closed-circuit television to warn his work force what was at stake.
"I said, 'This is secret. This can't be the second half of a sentence that begins, 'Honey, you won't believe what happened to me at work today,'" Hayden said. "NSA headquarters was brain dead. We had some residual ability at our locations around the world, but I don't want to trivialize this. This was really bad."
The computers were back up in three and a half days, but there was no denying the enormity of what had happened. The NSA's problems went beyond overworked computers. But almost none of this was understood outside the highly secretive organization.
The National Security Agency is the largest spy agency in the United States, and perhaps the world. Twice as big as the CIA, the NSA eavesdrops on communications worldwide.
News cameras have never been allowed inside the ultra-secret agency - until now. Martin provides a look at America's most secret spy agency, which is on 350 acres south of Baltimore, studded with giant antennas and protected by barbed wire and guard dogs.
A phone call intercepted by the NSA is often the first warning that a terrorist such as Osama bin Laden is planning an attack against Americans. To find that threatening phone call, email or radio transmission among the billions made daily, the NSA relies on rooms of supercomputers.
Does the NSA eavesdrop? "We're involved in signals intelligence," Hayden said.
Signals intelligence means operating listening posts all over the world to intercept billions of radio transmissions, phone calls, emails and faxes and to uncover terrorist plots and other foreign threats to the United States.
But the NSA will never reveal what all these antennas are listening to.
"If the target didn't think he or she was communicating privately, they wouldn't communicate," Hayden said. "The key to this business is actually doing what your adversary believed to be impossible."
Conversations of air defense gunners preparing to take a shot at an American plane over Iraq are monitored and warnings are sent out via a top-secret chat room.
The NSA has a gamut of security devices to protect its secrets. There is a finger identification system and scanners that can recognize eyeballs.
Office keys are never taken home - they're issued by machine each morning. Some of what goes on here is straight out of a James Bond movie. Dave Murley is working on a computer that can recognize a face. It allows access to computers only when it recognizes the face of an authorized user.
At the NSA even the trash is a government secret. The NSA gets rid of 40,000 pounds of classified documents each day, by recycling them into pulp shipped off to become tissue paper.
Until recently NSA employees were forbidden to tell their neighbors or families their profession.
On any given day, the majority of intelligence that shows up in the president's morning briefing comes from the NSA, considered by many to be the cornerstone of American intelligence.
Some might therefore be alarmed to read a report by a team of NSA insiders concluding that the "NSA is in great peril."
"We're behind the curve in keeping up with the global telecommunications revolution," Hayden said.
The NSA is now trying to play catch-up to Silicon Valley and the cell phones and computers that have proliferated throughout the world.
"In the previous world order, our primary adversary was the Soviet Union," Hayden said. "Technologicaly we had to keep pace with an oligarchic, resource-poor, technologically inferior, overbureaucratized, slow-moving nation-state."
"Our adversary communications are now based upon the developmental cycle of a global industry that is literally moving at the speed of light ... cell phones, encryption, fiber optic communications, digital communications," he added.
Documents introduced at the trial of the four men convicted of blowing up two American embassies in Africa indicate that the NSA was monitoring Osama bin Laden's satellite phone as he allegedly directed preparations for the attack from his hiding place in Afghanistan. Even so, the NSA was unable to collect enough intelligence to stop it.
"Osama bin Laden has at his disposal the wealth of a $3 trillion-a-year telecommunications industry," Hayden said.
From about 1996 to 1998, when bin Laden was beginning his operations out of Afghanistan, NSA knew his phone number and was able to listen in on phone calls he and his top lieutenants made to Al Qaida cells around the world. But the terrorists were so careful and cryptic about what they said over the phone that the U.S. was caught totally by surprise when in August of 1998 truck bombs detonated simultaneously outside the American embassies in Kenya and Tanzania, killing 224 people.
One of the terrorists arrested after those bombings gave NSA another phone number - this one belonging to a cell phone in Yemen. Listening in on that phone gave the NSA one of the first leads that might have uncovered the 9/11 plot - two men were headed to a meeting of terrorist operatives in Malaysia. NSA immediately passed the information to the CIA.
The meeting took place in a high-rise apartment building on January 6, 2000. The CIA didn't have time to plant any listening devices, but it was able to get pictures of the two men, who later turned out to be two of the hijackers who flew into the Pentagon. On January 15, 2000, the two hijackers entered the U.S. Nine days later NSA suffered its computer meltdown.
The NSA's nightmare is terrorists like Osama bin Laden using technology developed in the United States to hide their plans to attack Americans.
One way they can do it is via a software program to make messages unreadable.
An independent computer programmer, Phil Zimmermann, developed the program, which he calls Pretty Good Privacy. He distributes it for free on the Internet as a protest against government surveillance.
"We don't want to leave behind the privacy that we enjoyed before all this new technology came in," Zimmerman said.
This is cryptography for the masses. "I can't think of a way of making it available to the good guys without also making it available to the bad guys," Zimmerman said.
So a person who wants to protect their credit card number has the same access to Pretty Good Privacy as a terrorist. "It bothers me a great deal but I don't know how to solve that problem," he said.
And that's a big problem for the NSA, which has top-of-the line supercomputers - some of them capable of performing more than 1 trillion operations per second - to help decipher unreadable jumbles of letters and numbers.
They are increasingly hard-pressed to keep up with the sheer volume of traffic. As the demands grow, the system is stretched thinner and thinner. Until they broke down completely in the January 2000 incident that Hayden calls the ultimate wake-up call.
It wasn't Hayden's first wake up call. When he became director three years ago, Hayden commissioned two studies of the organization and received a scathing indictment of a stagnant and unwieldy government bureaucracy. There is "confusion and paralysis," the reports said. "We have run out of time."
Hayden has not spoken publicly about what if any blame NSA deserves for the intelligence failure of September 11th. But last year we asked him if NSA had overlooked any warnings of another Al Qaida attack - the bombing of the USS Cole in Yemen, killing 17 Americans. He told us he personally checked and NSA hadn't missed a thing. It just wasn't there.
"When the Cole disaster took place I had brought to my desk in, in this office, every stitch of NSA reporting on the - that could in any way be related to this. And I went thought it report by report and I sent a letter out to our entire work force, which was essentially, you performed well. Keep up the good work.
"It sounds like the operation was a success but the patient died," says Martin.
"It's a dangerous world out there, David," Hayden responded. "I can't guarantee you, in fact, I would refuse to guarantee you that even if we were at the top of our game that ill things won't happen to Americans."