One day last year, a trusted courier for Osama bin Laden answered a phone call that might have been wholly unremarkable except for one thing — the National Security Agency was apparently listening in.
That intercepted call helped American intelligence officials track the courier all the way to the walled compound in Pakistan where bin Laden was hiding. The discovery eventually led to last week's midnight assault by Navy SEALs who killed the al-Qaida leader, ending a pursuit that began in the mid-1990s.
A spokeswoman for the NSA said the agency would not offer more detail, and intelligence officials won't even confirm the account, which was reported by several news outlets quoting anonymous sources. And yet for the super-secret NSA, one of Maryland's largest employers with a work force of some 30,000 and a budget in the billions, this singular act of eavesdropping now stands as one of its most notable and conspicuous achievements.
While news coverage has largely focused on the raid itself and the Central Intelligence Agency interrogations that yielded the courier's identity, observers of the U.S. intelligence community say credit also belongs to two Maryland-based intelligence agencies: the NSA in Fort Meade, which scours global communications for clues, and the National Geospatial-Intelligence Agency in Bethesda, which provides mapping and other information.
"That is the important part of the story that has not been fully told yet," said John V. Parachini, director of the Intelligence Policy Center at the RAND Corp. The two agencies increasingly do much more than gather vast quantities of information, he said: "It's not just collecting bits and bytes and squeaks and peeps, but putting those into context."
Rep. C.A. Dutch Ruppersberger of Baltimore County said bin Laden's killing has vindicated an intelligence community that endured criticism for years as the terrorist leader eluded the grasp of his American pursuers. The ranking Democrat on the House Permanent Select Committee on Intelligence, Ruppersberger said the bin Laden raid would not have been possible without an array of contributions from various agencies, including the two in Maryland along with the CIA and the military.
"We have now sent a message to the world," he said. "If you're going to attack the United States of America, kill Americans, we're going to find you and bring you to justice."
Details of the bin Laden raid, and all that led up to it, remain shrouded in secrecy. Marci Green, the NSA spokeswoman, declined to comment. She said NSA's budget is classified, as is the number of employees who work at the sprawling headquarters off the Baltimore-Washington Parkway.
But published accounts quoting senior government sources, and interviews with analysts and lawmakers who know how the Maryland-based spy agencies operate, create a rough sketch of how the persistence and sophistication of a mammoth government program was able to ferret out information that helped bring down the world's most wanted man.
The Washington Post published a partial transcript of the phone call, intercepted by the NSA, that put government investigators onto bin Laden's trail. Citing unnamed U.S. sources briefed on the operation, the newspaper said the call came from an old friend of bin Laden's courier, who asked him: "What's going on in your life? And what are you doing now?"
"I'm back with the people I was with before," he answered, according to The Post's account.
The friend, realizing that answer probably meant the courier was with bin Laden, replied: "May God facilitate."
Ruppersberger could not share most of what he knows because it is highly classified. But he was quick to praise the NSA's eavesdropping capabilities. "Just think of the volume of conversations, both Internet and cell phones, that NSA collects around the world," he said.
Parachini of RAND said the rule of thumb has been that every six hours, NSA collects an amount of information equivalent to the store of knowledge housed at the Library of Congress.
"The volume of data they're pulling in is huge," he said. "One criticism we might make of our [intelligence] community is that we're collection-obsessed — we pull in everything — and we don't spend enough time or money to try and understand what do we have and how can we act upon it."
According to John Pike, director of the private national security group GlobalSecurity.org, the NSA relies on powerful computers to flag important conversations, such as the one involving the courier.
"They're listening for words, phrases, sentences that make no sense — 'The angry red fox jumps over the moon at dawn.'" In addition to coded conversations, the computers also listen for obvious red flags like "bomb," "plot" and "jihad."