Early Warning Was Still Too Late
President Bush did not know in advance, and could not have been expected to know, the specifics of how Qaeda members would commandeer airplanes and fly them into prominent buildings. And most of the steps taken since September could not realistically have been implemented based on what was known last summer. Patrols by fighter jets over American cities and tighter inspections of passengers and luggage at airports would have been difficult to justify based on the information available.

Nonetheless, the administration and intelligence community appear to have made important mistakes in the weeks before the attacks. The Bush administration believed Al Qaeda might resort to hijacking only in the traditional sense — seizing an airplane and treating its passengers as hostages for bargaining purposes. But the idea that Al Qaeda would engage in only a traditional hijacking should have been seen as doubtful. Well before Sept. 11, we knew that Al Qaeda and its affiliates were not traditional terrorists. Their record showed that they would try to kill as many Americans as possible using whatever new tactics they could devise.

Qaeda and Islamic extremists had already tried to destroy the World Trade Center towers in 1993. Sheik Omar Abdel Rahman and others had designs to destroy infrastructure like New York's Lincoln Tunnel. Qaeda terrorists had killed hundreds in the 1998 attacks against American embassies in Kenya and Tanzania. On the eve of the millennium, an operative linked to Osama bin Laden, Ahmed Ressam, tried to sneak into the United States to bomb Los Angeles International Airport. And a Qaeda affiliate, Ramzi Yousef, had developed plans to blow up a dozen American jumbo jets in the mid-1990's. By the late 1990's, intelligence services should have recognized that Qaeda hijackers would be likely to kill everyone on board any plane they seized.

Issuing an alert based on such information to intelligence and law enforcement agencies and airlines might have caused people to respond differently. For years, airline pilots had been told not to resist hijackers in most circumstances, in the hope that negotiating with them stood the best chance of preventing loss of life. It would have made sense to revise this approach once we began to realize that we were confronting a new type of terrorist.
http://www.nytimes.com/2002/05/18/opinion/18OHAN.html?todaysheadlines