We cannot count on education to end the threat of terrorism; indeed, many of the suicide hijackers of Sept. 11 were highly educated.

It was also the period in which most of the suicide hijackers entered the United States and made their final preparations for attack.

But many passengers today boarded their flights with a clenched jaw and determination, as if daring a suicide hijacker to try again.

Mr. bin al-Shibh, a young Yemeni, was apparently in close contact with the suicide hijackers in the weeks before the attacks.

The B.I.S. report of the meeting that Saddam's case officer had with the suicide hijacker fell precisely within those dates.

The official said several of the suicide hijackers were members of the sheik's tribe.

Having been sentenced to 15 years in prison for providing support for some of the suicide hijackers, Mr. Motassadeq was freed in April.

On 9/11, the suicide hijackers did not make any attempt to contact ground control to inform anyone about their hijackings, nor engage in any dialogue or negotiations at all.

On Tuesday morning, in his first public statement about the attacks, the president had called the suicide hijackers "folks."

The existence of the internal warnings about Mr. Moussaoui and the possibility that he was a suicide hijacker had been previously disclosed.