In all likelihood in the mid-1990s the National Security Agency was listening to the communications traffic flowing through the Umm Haraz satellite ground station outside Khartoum, Sudan.
The reason: Osama bin Laden then lived nearby. According to an expert on the history of US eavesdropping, the NSA had identified the phone numbers used by Mr. bin Laden and key associates. Intercepts yielded a trove of data about the financing and organization of the fledgling Al Qaeda.
Fast forward to 2006. Bin Laden has decamped for parts unknown, and the NSA has no Umm Haraz equivalent. Al Qaeda's communications no longer follow a well-worn track that's easy to intercept.
It's in this context that the current controversy over the NSA's domestic eavesdropping activities might be seen, say some experts. The nation's biggest and most secretive intelligence agency is struggling to tap an adversary for whom the very nature of communication has changed.
Following the 9/11 terrorist attacks, President Bush authorized the NSA to eavesdrop, without a warrant, on the international communications of people in the US, when the agency believed those communications were linked to Al Qaeda.
Revelation of this program in a leaked story in The New York Times in December sparked widespread controversy, and lawsuits. The American Civil Liberties Union filed suit against the NSA itself on Jan. 17. On Jan. 31, another civil liberties group, the Electronic Frontier Foundation, sued AT&T for its alleged cooperation with the NSA eavesdropping.
Now, White House officials are beginning to testify publicly about the controversy. Before a Senate committee Thursday focused on international security threats, National Intelligence Director John Negroponte said the eavesdropping program was crucial for protecting the US against terrorism. On Monday, at a Senate Judiciary Committee hearing on the disputed program, Attorney General Alberto Gonzales is expected to appear. Although committee chairman Sen. Arlen Specter (R) of Pennsylvania has given him a list of questions he would like answered, there's another question he is unlikely to ask in open session - or, at least, not in too-specific terms. Has the NSA developed eavesdropping technology that does not fit easily into the strictures of the 1978 law that sets out procedures for obtaining warrants in such situations?
"There are a lot of capabilities out there that were not envisioned when the law was passed," says Daniel Byman, director of Georgetown University's security studies program.
Some 10 years ago, the NSA did pick up phone conversations that linked Al Qaeda with numerous operations, wrote independent historian Matthew Aid in a 2003 journal article on signals intelligence and the terror fight.
Through much of its history, including bin Laden's time in Sudan, Al Qaeda operatives maintained poor communications security, he wrote. "The public record shows that [between 1993 and 2003] bin Laden and his operatives broke virtually every basic tenet of good spying tradecraft, the most important commandment of which was and remains never to speak about one's operations using communications means that can be intercepted."
Administration officials have insisted that the warrantless eavesdropping is a focused program from which the vast majority of Americans have nothing to fear.
On Jan. 23, former NSA director Gen. Michael Hayden, in an appearance at the National Press Club, said that the program "is not a drift net over Dearborn or Lackawanna or Fremont, grabbing conversations that we then sort out by these alleged keyword searches or data-mining tools."
The implication is that this eavesdropping is analogous to old- fashioned FBI mob wiretaps, in which law enforcement first identifies a target person or number, and only then affixes alligator clips to a phone line somewhere to listen in.
But it's possible that General Hayden has just chosen his words carefully, some experts say. Given the NSA's massive size, and the dire nature of the terrorist threat, it would be surprising if the agency had not tried to develop cutting-edge techniques that old gumshoes might not recognize.
NSA has had the ability to do automatic speech and voice recognition for at least a decade, says John Pike of GlobalSecurity.org. It may have the technical capability to essentially monitor all electronic communications crossing US borders.
The key here may be what Hayden meant when he said "grabbing conversations." Having phone and e-mail traffic flow though NSA computers may be one thing. A computer identifying something that might be important, such as a combination of phrases that could indicate a sleeper cell communication, and pulling it out, is another. News reports say its effort to update its technology has fallen behind and generated huge cost overruns.
"The NSA has been routinely listening to US persons all along. What they have not done in the past is create a record on US persons," says Mr. Pike.
Hayden, however, has been adamant that the NSA respects Americans' privacy, and that no one has been subject to warrantless listening unless they were believed to be linked in some manner to Al Qaeda.