THE REVELATION by the New York Times of an NSA program to review international communications could only cause surprise among those unfamiliar with the history and mission of the agency. The National Security Agency descended from various post-WWII military signal agencies, a centralized and civilianized intelligence service focused on one task: the exploitation of international communications to keep the United States from suffering another Pearl Harbor.

Given that we had suffered just that kind of attack on September 11, 2001 by allowing existing law to have the most negative interpretation possible for coordination between law enforcement and intelligence services--which would create a storm of criticism from the 9/11 Commission and Congress--the NSA understandably took center stage for the defense of the United States. Combined with the Patriot Act, the government took the position that a wartime administration not only needed to ensure greater cooperation and coordination between agencies, but to get better intelligence on which to act. The discovery that the al-Qaeda terrorists operated with impunity from the American homeland for months, openly communicating with Osama bin Laden's network from cell phones and email provided by American networks, showed the necessity of watching this front of the war much more carefully.

That may have ended with the publication of the program by the New York Times. It may end not because of any illegality, but because the revelation of the scope of our intelligence collection will warn terrorists about their methods of communication. They will likely adapt their tactics. So why,

Since the Times story broke, the public has received varying descriptions of what the paper actually reported, with the bogus charge that the NSA had spied on American citizens getting the most repetition. Of course, that allegation never appears in the Times article. Reporters James Risen and Eric Lichtblau carefully avoided making that charge, and it makes a difference:

Under a presidential order signed in 2002, the intelligence agency has monitored the international telephone calls and international e-mail messages of hundreds, perhaps thousands, of people inside the United States without warrants over the past three years in an effort to track possible "dirty numbers" linked to Al Qaeda, the officials said. The agency, they said, still seeks warrants to monitor entirely domestic communications.

The previously undisclosed decision to permit some eavesdropping inside the country without court approval was a major shift in American intelligence-gathering practices, particularly for the National Security Agency, whose mission is to spy on communications abroad. As a result, some officials familiar with the continuing operation have questioned whether the surveillance has stretched, if not crossed, constitutional limits on legal searches.

Bush's critics have mostly argued that the NSA violated the Foreign Intelligence Surveillance Act by failing to secure warrants before performing a "search" on these international communications. However, FISA gives wide latitude to the government when such communication does not involve a "U.S. person." FISA authorizes warrantless surveillance in its opening chapter: