Hours after the attacks of Sept. 11, top National Security Agency officials paid a calming visit to the NSA's counterterrorism office. Workers there were emotionally wrought, due to both the stress of the day and the counterterror division's location - the vulnerable top of a high-rise at NSA's suburban Maryland location.
By the afternoon, they had recovered and were defiantly tacking up blackout curtains to mask their location, according to Lt. Gen. Michael Hayden, then the NSA's director.
Now the NSA is being roiled by political controversy over charges that it is illegally eavesdropping on Americans. President Bush is scheduled to visit the agency Wednesday as part of a week-long effort to defend a program the administration claims is both legal and crucial in the fight against terror.
If nothing else, the uproar is adding another chapter to the history of an arm of the government that has been derided and lauded by turns ever since the US government first publicly acknowledged its existence.
In the 1970s, for instance, the NSA drew intense criticism for its role in spying on critics of the Vietnam War and other political opponents of the Nixon administration.
But that sort of subversive behavior isn't what is at issue today, notes one administration critic. "No one is suggesting the NSA is monitoring Hillary Clinton," says Steven Aftergood, director of the Project on Government Secrecy at the Federation of American Scientists.
Founded by order of President Truman in 1952, the NSA is today headquartered at Fort Meade, an Army reservation that sits near the midpoint of the Baltimore-Washington Parkway.
In the NSA's early years, the US government did not publicly acknowledge it. NSA stood for "no such agency," joked its employees.
That changed with the 1973-76 investigations of US intelligence abuses by Sen. Frank Church (D) of Idaho. The NSA had kept a "watch list" of US citizens and organizations whose foreign communications it intercepted, it turned out. The NSA had also kept copies of most telegrams sent from the United States to foreign countries.
The response to these revelations was the 1978 Foreign Intelligence Surveillance Act, or FISA - a law that set judicial procedures for requesting electronic surveillance of persons thought to be engaged in espionage or terrorism against the US.
Today the NSA is in the curious position of being both secretive and famous. Its work remains so closely held that its director seldom appears in public. Yet it has starred (as the villain) in at least one recent feature-length movie, "Enemy of the State." The NSA itself, perhaps to bolster its image, has created a website for children, which features the Cryptokids, an assortment of cartoon animal characters who, in games, carry out code-breaking assignments and other espionage activities.
Following the fall of the Berlin Wall, and the loss of the agency's cold-war mission of eavesdropping on everything from Soviet missile telemetry to the car-phone calls of Kremlin leaders, the NSA lost about one-third of its budget, and one-third of its manpower.
At the same time, in the decade of the 1990s the world saw an explosion in what NSA experts call "packetized communications" (what the rest of the world calls e-mail and other computer missives). Also, cellphone use increased 50 times over in the '90s, noted General Hayden, now principal deputy director of national intelligence, in a 2002 congressional hearing. US international phone calls went from 38 billion minutes to over 100 billion minutes annually.
Faced with a new enemy - Al Qaeda - that communicated as little as possible, and in constantly changing ways, the NSA was forced to become "hunters rather than gatherers," in a phrase used by its former director of signals intelligence, Maureen Baginski.
Today, Ms. Baginski has moved on. In 2003, she was named the FBI's first-ever executive assistant director of intelligence. And the NSA is under fire for what critics deem is hunting for intelligence a bit too much.
Under the domestic eavesdropping program - administration officials prefer to call it a "terrorist surveillance program" - the NSA since 2002 has been listening in on international communications of some people in the US, when those communications are thought to be connected to possible terror activity.
But officials have not been requesting warrants from the special court established by the FISA law to handle just such situations.
The president does not need to do so, according to the White House, because of the inherent powers of his office and because of authority conveyed by post-9/11 congressional resolution.
Critics say it may be because the eavesdropping in question may not reach the legal thresholds required by the FISA law.
"Why wouldn't they stay within the legal framework if that was an option?" says Mr. Aftergood of the Federation of American Scientists.
Defending the NSA's efforts in an extremely rare question-and-answer session before the National Press Club on Monday, Hayden said that the FISA statute "does not give us the operational effect" needed.
In other words, even the emergency aspects of the law, which allow wiretaps for a short period of time before applying for a warrant, don't move fast enough for NSA purposes.
The 9/11 commission criticized the NSA's inability to link things happening in the US with things happening elsewhere, pointed out Hayden. The presidential authorization program allows the agency to more quickly track calls judged to be connected to Al Qaeda in some manner.
"The trigger is quicker and a bit softer than it is for a FISA warrant, but the intrusion into privacy is also limited: only international calls, and only those we have a reasonable basis to believe involve Al Qaeda or one of its affiliates," said Hayden.
The program isn't a "drift net" that will capture the phone calls home of a US student on international study who uses the word "jihad," claimed Hayden.
And the former director of the NSA said he was disappointed that the default response for critics was to assume the worst about the eavesdropping agency.
"I'm trying to communicate to you that the people who are doing this go shopping in Glen Burnie, [Md.] ... and they know the law," said Hayden.
It's possible that Hayden and the Bush administration are describing a program that is focused on early warning and is processing too many international calls for the FISA court process to handle, noted critics.