In a few interviews I've done recently, I've made the statement that I don't think that most Americans are aware of this, from Sibel's Open Letter to Kean & 911Comm:
More than four months prior to the Sept. 11 terrorist attacks, in April 2001, a long-term FBI informant/asset who had been providing the bureau with information since 1990, provided two FBI agents and a translator with specific information regarding a terrorist attack being planned by Osama bin Laden. This asset/informant was previously a high-level intelligence officer in Iran in charge of intelligence from Afghanistan. Through his contacts in Afghanistan, he received information that: 1) Osama bin Laden was planning a major terrorist attack in the United States targeting four or five major cities; 2) the attack was going to involve airplanes; 3) some of the individuals in charge of carrying out this attack were already in place in the United States; 4) the attack was going to be carried out soon, in a few months. The agents who received this information reported it to their superior, Special Agent in Charge of Counterterrorism Thomas Frields at the FBI Washington Field Office, by filing 302 forms, and the translator translated and documented this information. No action was taken by the special agent in charge, and after 9/11 the agents and the translators were told to "keep quiet" regarding this issue. The translator who was present during the session with the FBI informant, Mr. Behrooz Sarshar, reported this incident to Director Mueller in writing, and later to the Department of Justice Inspector General. The press reported this incident, and a report in the Chicago Tribune on July 21, 2004, stated that FBI officials had confirmed that this information was received in April 2001.I've felt a bit tentative saying: "I don't think that most Americans are aware of this" - because I was never really sure how many people are familiar with this story... As it happens, Scott asked Michael Scheuer, head of the Bin Laden unit, Alec Station, about this, and even he isn't aware of it, in 2007.
Separately, Scheuer says that the 911Commission will be more responsible than anyone for the next terrorist attack in the US.