The CIA itself also had its own spectacular failure in the run up to 9/11, which wasn’t a failure to collect intelligence, but a failure of information sharing. The CIA had quite a bit of information about two of the hijackers and their presence in the United States before 9/11, which the agency didn’t share with other government agencies until it was too late to do anything about it.

The government missed multiple opportunities to catch al Qaeda hijacker Khalid al-Mihdhar when he was living in San Diego for a year and a half in the run up to 9/11, not because it lacked access to all Americans phone records but because it didn’t share the information it already possessed about the soon-to-be hijacker within other branches of the government.

The missed opportunities in the al-Mihdhar case are well-documented. The CIA failed to “watch-list” al-Mihdhar and another suspected al Qaeda terrorist, Nawaf al-Hazmi, whom the agency had been tracking since they attended an al Qaeda summit in Malaysia on January 5, 2000.

The failure to put Mihdhar and Hamzi on a watch list meant that immigration and law enforcement authorities were not alerted to their presence when they entered the United States under their real names. Ten days after the meeting in Malaysia, on January 15, 2000, al-Hazmi and al-Mihdhar flew into Los Angeles.