• Conspirator Khalid Almihdhar, who was (at least theoretically) under U.S. surveillance for his suspected role in the bombing of the USS Cole, aroused suspicion at a San Diego flight-training school with his impatient request that he be taught how to fly a Boeing jet. (On 9/11, Almihdhar would help crash American Flight 77 into the Pentagon, killing 189 people.)
• Another conspirator, Nawaf Alhazmi, aroused suspicion when he boasted to a fellow gas-station employee that he would become famous. (Alhazmi would go down with Almihdhar on Flight 77. For more on what the Federal Bureau of Investigation knew about Almihdhar and Alhazmi prior to 9/11, click here.)
• By late July, former Central Intelligence Agency chief George Tenet told the 9/11 Commission, "the system was blinking red," and earlier that same month, FBI special agent Kenneth Williams sent a memo from the Phoenix office to Washington noting "an inordinate number of individuals of investigative interest" attending flight school in Arizona. (To read the memo, click here.)
• In early August, President Bush received a classified daily brief famously titled "Bin Laden Determined To Strike in U.S." (To read it, click here.)
• Later in August, the FBI's Minneapolis office interrogated Zacarias Moussaoui, who had aroused suspicion at a Minnesota flight school by asking about New York City flight patterns and whether a jetliner's cockpit doors could be opened while it was airborne. (To read a summary of what the Minneapolis office knew as of Aug. 19, click here.) Moussaoui's recklessness and volatility made his al-Qaida superiors reluctant to use him in the 9/11 attack; he was likely being held in reserve for a future al-Qaida attack, or possibly as a backup pilot for 9/11.
• In trying to obtain a warrant to examine Moussaoui's laptop, a field officer in the FBI's Minneapolis office told FBI headquarters that he was "trying to keep someone from taking a plane and crashing into the World Trade Center." The FBI did not obtain the evidence of Moussaoui's al-Qaida link deemed necessary to obtain that warrant until two days after 9/11.
Nearly eight years after the attacks, it remains physically sickening to review these for-want-of-a-nail details about what the U.S. government knew prior to 9/11. The various intelligence agencies' failures to pool their knowledge about the plot should surprise no one familiar with Washington's bureaucratic culture. But it's equally true that to count on so extreme a degree of government dysfunction, as al-Qaida effectively did, was foolhardy in the extreme. The terrorists took an unacceptably high risk that they'd get caught, and, just barely, they beat the odds. That they succeeded does not prove they were smart to try.
Nor is it clear that they were smart to succeed. In Afghanistan, the 9/11 attacks provoked a furious response from the United States military that destroyed al-Qaida's infrastructure of terrorist training camps and cave dwellings; unseated al-Qaida's protectors, the Taliban; and captured or killed two-thirds of al-Qaida's leaders—most notably, Khalid Sheikh Mohammed, 9/11's principal architect and now Guantanamo's best-known prisoner. According to Lawrence Wright, author of the Pulitzer Prize-winning The Looming Tower: Al-Qaida and the Road to 9/11, nearly 80 percent of al-Qaida's Afghanistan-based membership was killed in the U.S. invasion; intelligence estimates suggest al-Qaida's current membership may be as low as 200 or 300. At the very least, U.S. forces set back the al-Qaida hierarchy by several years. At most, the United States may have destroyed permanently al-Qaida's ability to operate as a centrally run enterprise, reducing its chairman, Osama Bin Laden, and its CEO, Ayman al-Zawahiri, to symbolic figureheads rather than hands-on leaders. Meanwhile, al-Qaida's goal of re-establishing the 1,000-year Islamic caliphate that sprawled across three continents until the early 20th century remains distant as ever.(The counterargument is that in striking back at Afghanistan and especially Iraq, the United States did itself incalculable damage by alienating much of the Muslim world while committing more blood and treasure than it could afford to lose. I elaborate this case in "The Time-Space Theory," at the opposite end of the worry spectrum.)
Despite some initial euphoria, 9/11 and its bloody aftermath appear to have worsened al-Qaida's standing not only among Muslims generally but even (Peter Bergen and Paul Cruikshank argued in a June 2008 New Republic article) among jihadis, who have observed that 9/11 led to the death of many more Muslims (especially in Afghanistan and Iraq) than anyone else. Many of these Muslims were killed directly by al-Qaida and other Islamist terrorists. In Overblown: How Politicians and the Terrorism Industry Inflate National Security Threats, John Mueller, a political scientist at Ohio State, relates how al-Qaida-linked coordinated suicide bombings in three Jordanian hotels in 2005 ended up killing a large group of Palestinians and Jordanians who were attending a wedding party. "It would be difficult," Mueller writes, "to imagine a target likely to be more stupid from the perspective of the terrorists." Members of al-Qaida in Iraq, an insurgent group affiliated with al-Qaida, alienated their fellow Sunnis by targeting civilians, imposing Taliban-style repression and provoking attacks from the country's Shiite majority. In response, Sunni militias banded together to form the Awakening, a U.S.-funded fighting force that, depending on whom you ask, deserves either some or most of the credit usually given to the U.S. troop surge for reducing the level of violence in Iraq since 2006.