This does not answer the question.
If the CIA or FBI knew the plot, they would stop it as it happened, or before. Looks like no one knew the plot, except 19 nuts from UBL.
The CIA and FBI HQ did not need to know the plot in detail in order to stop it, they had the names of Khalid al-Mihdhar and Nawaf al-Hazmi on August 22, 2001, three weeks ahead of the attacks on 9/11, and knew these al Qaeda terrorists were in the United States in order to take part in this huge al Qaeda terrorist attack that would kill many Americans.
The credit cards of these two terrorists were used to purchase tickets for 10 of the al Qaeda terrorists on 9/11. They even knew that Saudi Arabian Airlines had Mihdhar’s credit card number and even knew that both Mihdhar and Hazmi had visas for the US. Had the CIA or FBI checked with the State department, they could have found Hazmi’s California address on the visa request that he used to get a new visa when his old one expired.
Instead of stopping this attack, FBI HQ agents and managers, under orders from former CIA manger Tom Wilshire, who had moved over to the FBI HQ in mid-May 2001, illegally shut down FBI Agent Steve Bongardt's investigation of Mihdhar and Hazmi. It is clear that in July 2001 Blee, Black and Tenet had ordered Wilshire to essentially sabotage any potential criminal investigation of Mihdhar and Hazmi by the FBI criminal agents on the Cole bombing, which he did when he ordered Corsi to illegally block Bongardt’s investigation for these two al Qaeda terrorists.
On August 29, 2001 Corsi sent an email to FBI Agent Stave Bongardt and told him that "at such time as evidence is developed of a substantial Federal crime (by Mihdhar and Hazmi) this information would be passed over the wall" for Bongardt to do a follow up investigation. But according to the DOJ IG report, on page 301, it says that Corsi knew on August 22, 2001 that the CIA had a photo of Walid bin Attash taken at Kuala Lumpur, knew that both Mihdhar and Hazmi had also been at Kuala Lumpur, and hence knew that Mihdhar and Hazmi had taken part in the planning of the Cole bombing that had taken place at this al Qaeda planning meeting. So not only did she have proof of a substantial Federal crime by Mihdhar and Hazmi six days before she shuts down his criminal investigation of Mihdhar and Hazmi, she even knew that because of this information she herself was committing a Federal crime by withholding this information from Bongardt and his team.
On August 30, one day later, the CIA sent Rod Middleton, Corsi’s boss, this photo of Walid bin Attash taken at Kuala Lumpur. Middleton had been on the phone with Corsi shutting down Bongardt’s investigation, when Middleton got this photo, so he knew that both he and Corsi were committing a major Federal felony of criminally obscuring the investigation onto the murders of 17 US sailors by not giving this information to Bongardt and then working to block his investigation of these two al Qaeda terrorists. By obstructing this investigation they allowed the attacks on 9/11 to take place.
This information, which is now in the public domain, was covered up by the Joint Inquiry Committee of the house and the Senate and by the 9/11 Commission who said that 9/11 happened because of a failure of imagination.
Because the CIA manages that had asked Wilshire to sabotage Bongardt’s investigation of Midhar and Hazmi knew full well that this would allow the al Qaeda terrorists to carry out the attack the CIA have been warned about, as did Wilshire, Corsi and Middleton, it is clear that both the CIA and FBI HQ had deliberately allowed the al Qaeda terrorists to murder almost 3000 people and clear that they got away with it due to a cover up by the corrupt officials who were overseeing these investigations.