Talking to the detainees was especially important because the commission was charged with explaining not only what happened, but also why it happened. In looking into the background of the hijackers, the staff found that religious orthodoxy was not a common denominator since some of the members "reportedly even consumed alcohol and abused drugs." Others engaged in casual sex.

Instead, hatred of American foreign policy in the Middle East seemed to be the key factor.

Speaking to the F.B.I. agents who investigated the attacks, Hamilton asked: "You've looked [at] and examined the lives of these people as closely as anybody. . . . What have you found out about why these men did what they did? What motivated them to do it?"

These questions fell to Supervisory Special Agent James Fitzgerald. "I believe they feel a sense of outrage against the United States," he said.

"They identify with the Palestinian problem,

they identify with people who oppose repressive regimes and I believe they tend to focus their anger on the United States." As if to reinforce the point, the commission discovered that the original plan for 9/11 envisioned an even larger attack. Khalid Shaikh Mohammed, the strategist of the 9/11 plot, "was going to fly the final plane, land it and make 'a speech denouncing U.S. policies in the Middle East,"' Kean and Hamilton say, quoting a staff statement. And they continue:

"Lee felt that there had to be an acknowledgment that a settlement of the Israeli-Palestinian conflict

was vital to America's long-term relationship with the Islamic world, and that the presence of American forces in the Middle East was a major motivating factor in Al Qaeda's actions."

Intelligence Test
By JAMES BAMFORD AUG. 20, 2006
https://www.nytimes.com/2006/08/20/books/review/intelligence-test.html