Diverd4777 wrote:

http://www.cnn.com/2004/ALLPOLITICS/...arke.truth.tm/

In theory, greater vigilance at home might have exposed their conspiracy. There
were clues.

Two of the hijackers, Khalid al-Midhar and Nawaq al-Hamzi, were sought by the
FBI and the CIA as suspected terrorists.

An FBI agent in Phoenix, Arizona, had noted a pattern of Arab men signing up
for lessons at flight schools. Zacarias Moussaoui, the suspected 20th hijacker,
was learning to fly in Minnesota, apparently without asking for landing
lessons.

Clarke argues that if the President had been demanding action every day from
his top aides, they would have passed the heat down the chain of command, and
perhaps connections would have been made.

I think you summed it up right at the beginning! 'In theory...'