The Mossad apparently warned their American counterparts several times about the terrorists, especially about al-Midhar. … Apparently not until shortly before September 11 did the CIA recognize that al-Midhar was dangerous and asked law enforcement agencies to look for him.
“FBI Agent Was Prevented From Relaying Warning on 9/11 Hijackers“:
More than a year before 9/11, CIA officials prevented an FBI agent working with the CIA from passing vital information to his agency on two suspected al Qaeda members — men who later would become Sept. 11 hijackers.
U.S. officials told ABCNEWS the agent wanted to warn his FBI bosses about a gathering in Malaysia where al Qaeda suspects Khalid Al-Midhar and Nawaq Alhamzi met with suspects in the Oct. 12, 2000, bombing of the USS Cole off the coast of Yemen.
After the meeting, CIA officials learned Al-Midhar and Alhamzi had visas to enter the United States, the U.S. officials said. …
“If that information [got] disseminated, would it have had an impact on the events of 9/11?” asked Jack Cloonan, an ABCNEWS consultant who previously worked as an FBI agent assigned to pursue members of al Qaeda. “I’m telling you that it would have.” …
Al-Midhar left the United States and came back just two months before 9/11 attacks — no questions asked. He arrived at John F. Kennedy International Airport in New York, using his own name.
Also see “Blinking Red,” “Did Al Qaeda Exploit Government Jihad Support?,” and “Preserved in Amber, Blind to Terror.”