WASHINGTON — Twelve years after the Sept. 11 attacks, the National Security Agency is adding office space for a larger workforce and more powerful computers. Already bigger than the Pentagon in square footage, its footprint will grow by an additional 50 percent when construction is complete in a decade.
And that's just at its headquarters at Fort Meade, Md.
The technical spying agency has enlarged all its major domestic sites — in Colorado, Georgia, Hawaii, Texas and Utah — and those in Australia and Britain.
The hiring, construction and contracting boom is symbolic of the hidden fact that in the years after the Sept. 11 attacks, the NSA became the single most important intelligence agency in finding al-Qaida and other enemies overseas, according to current and former counterterrorism officials and experts. "We Track 'Em, You Whack 'Em" became a motto for one NSA unit, a former senior agency official said.
In recent weeks, both Congress and the public have been roiled by the disclosure of top-secret documents detailing the collection of U.S. phone records and the monitoring of emails, social-media posts and other Web traffic of foreign terrorism suspects and their enablers.
Lacking a strong informant network to provide details about al-Qaida in 2001, U.S. intelligence and the military turned to the NSA's technology to fill the void. The demand for information also favored the agency's many surveillance techniques, which try to divine the intent of people by vacuuming up and analyzing their communications.
"I can't think of any terrorist investigation where the NSA was not a preeminent or central player, " said Michael Leiter, former director of the National Counterterrorism Center.
One top-secret document recently disclosed by former intelligence contractor Edward Snowden, who is on the run from U.S. authorities, revealed that 60 percent of the president's daily intelligence briefing came from the NSA in 2000, even before the surge in its capabilities began.
"The foreign signals that NSA collects are invaluable to national security," the agency said in a statement Friday to the Washington Post. "This information helps the agency determine where adversaries are located, what they're planning, when they're planning to carry it out, with whom they're working, and the kinds of weapons they're using."
The story of the NSA's post-Sept. 11 history could begin in many places, including the parking lot of the CIA. There, in late 2001, a Navy SEAL paced inside a trailer with a telephone to his ear. The trailer had been hastily converted from a day care facility to an operations center for the CIA's covert armed drone program, which was about to kill one of its first al-Qaida targets, 8,000 miles away in Afghanistan.
On the line with the SEAL was the drone operator and a "collector," an NSA employee at the agency's gigantic base at Fort Gordon in Augusta, Ga. The collector was controlling electronic surveillance equipment in the airspace over the part of Afghanistan where the CIA had zeroed in on one particular person. The SEAL pleaded with the collector to locate the cellphone in Afghanistan that matched the phone number that the SEAL had just given him, according to someone with knowledge of the incident who spoke to the Washington Post on the condition of anonymity because of the sensitivity of the issue.
The collector had never before done such a thing. Before even intercepting a cellphone conversation, he was accustomed to first confirming that the user was the person he had been directed to spy on. The conversation would then be translated, analyzed, distilled and, weeks later, if deemed to be interesting, sent around the U.S. intelligence community and the White House.
The NSA collector took what was then considered a gigantic leap — from using the most sophisticated spy technology to record the words of presidents, kings and dictators to using it to kill a man in a terrorist group.
The revolutionary significance of that and other similar operations was quickly grasped by intelligence officials.
By September 2004, a new NSA technique enabled the agency to find cellphones of potential targets even when they were turned off.
At the same time, the NSA developed a new computer linkup into which the military and intelligence officers could feed every bit of data or seized documents and get back a phone number or list of potential targets.
Air Force Gen. Michael Hayden, former director of the NSA, said in an interview last week that he would tell people, "If we could do this half well, this will be the golden age of sigint," or signals intelligence.
The battlefield technology overseas was matched by a demand back home for data to mine using the NSA's sophisticated computers. An example revealed by Snowden is the bulk collection of telephone metadata — information about numbers dialed and the duration of the calls.
"We always adjust our efforts to exploit the foreign communications of adversaries and defend vital U.S. networks in accordance with national priorities and in full accordance with U.S. law," the NSA said in a statement to the Washington Post on Friday.