How the FBI let 9/11 happen: the smoldering gun was right there all the time.

• Author: Taylor, Jeff A.

THE TRIAL OF September 11 conspirator Zacarias Moussaoui provided definitive proof that the U.S. government missed some clear opportunities to stop the 9/11 attacks. Those missed opportunities had nothing to do with the legal restrictions later loosened by the PATRIOT Act. It was bureaucratic hierarchies and power trips that let the Federal Bureau of Investigation ignore the carefully gathered evidence of an attack.

The March 20 testimony of the Minneapolis-based FBI agent Harry Samit buries the notion that 9/11 was unpreventable. Beginning with Moussaoui's arrest on August 16, 2001, Samit mounted a global, indefatigable investigation of the man and concluded that an attack involving hijacked airplanes was imminent.

Michael Rolince, the former head of the FBI's International Terrorism Operations Section, smugly insisted at trial that Samit's "suppositions, hunches and suspicions were one thing," while "what we knew" was another. In short, he said Samit's investigation and leads were not enough: Moussaoui had to speak up for the FBI brass to hear anything.

When defense lawyer Edward MacMahon cross-examined Rolince--possibly the only time a government security official has been so challenged over 9/11--the disconnect between the official story and reality was plain. Rolince testified that he never read the 26-page August 18, 2001 memo Samit had sent to his office warning that Moussaoui wanted to hijack a plane and had the weapons with which to do it. Samit also wrote that Moussaoui "believes it is acceptable to kill civilians" and approves of martyrdom.

A day earlier, Samit had sent an e-mail to his direct superiors recounting Moussaoui's training on 747 simulators. "His excuse is weak," Samit wrote. "He just wants to learn how to do it.... That's pretty ominous and obviously suggests some sort of hijacking plan."

Rebuffed by his superiors and ignored by Rolince, Samit still sought out more information worldwide, from sources as diverse as the FBI's London, Paris, and Oklahoma City offices, the CIA's counterterrorism center, the Secret Service, the Immigration and Naturalization Service, the Federal Aviation Administration (FAA), and probably the National Security Agency. He was sufficiently alarmed by what he heard that he sent an August 21 e-mail requesting the Secret Service be informed that Moussaoui planned to visit the White House and was interested in flight training.

Samit testified that on August 22 he learned from the French that...