This is the first part in a series of eight exploring why the United States suffered no follow-up terror attacks after 9/11. To read the series introduction, click here.

The 9/11 attacks were heralded as the harbinger of a new era of foreign-based terrorism in the United States. What if they were really a fluke?

Al-Qaida’s successful elimination of the Twin Towers, part of the Pentagon, four jetliners, and nearly 3,000 innocent lives makes the terror group seem, in hindsight, diabolically brilliant. But when you review how close the terrorists came to being exposed by U.S. intelligence, 9/11 doesn’t look like an ingenious plan that succeeded because of shrewd planning. It looks like a stupid plan that succeeded through sheer dumb luck.

Consider:

• 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.

• Tenet, despite knowing “the system was blinking red,” did nothing after he was briefed about Moussaoui on Aug. 23. (To read Tenet’s “Terrorist Threat Review Update” for that day, click here.)

• 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.

Even some inside al-Qaida have come to view terrorism’s costs as too high. In June 2008, Wright profiled a founding leader of al-Qaida known as Dr. Fadl. The author of two books used by al-Qaida to recruit members, Dr. Fadl more recently wrote from his Egyptian jail cell, “We are prohibited from committing aggression, even if the enemies of Islam do that.” In Dr. Fadl’s view, the 9/11 attacks were suicidal not only for the hijackers but for al-Qaida as a whole. Writing in 2007, Dr. Fadl argued that it was immoral to fight Muslim heads of state if they were believers and that it was unwise to do so if these leaders possessed sufficient power to prevail. Quoting the Prophet Mohammed, Dr. Fadl wrote: “Those who rebel against the Sultan shall die a pagan death.” Dr. Fadl further argued that it was immoral under any circumstances to kill even non-Muslim civilians. These arguments stirred considerable debate in the Islamist world, and one can’t rule out that Dr. Fadl produced them under threat of torture. But they were seconded by a Kuwaiti cleric named Sheikh Hamid al-Ali, who has been identified by the U.S. Treasury as an al-Qaida fundraiser. Al-Qaida’s al-Zawahiri felt it necessary to write a lengthy rebuttal in which he claimed, preposterously, “no difference” between 9/11 and President Clinton’s 1998 bombing of the Al-Shifa pharmaeutical plant in Sudan (believed, mistakenly, to be an al-Qaida chemical-weapons facility). The 1998 bombing killed one night watchman—a tragic blunder, but hardly comparable to the deliberate slaughter of 3,000 noncombatants.

However nonsensical, al-Zawahiri’s views still prevail within al-Qaida. But does al-Qaida have the means for another U.S. attack? “Let’s have some healthy skepticism … when we read about these terrorist masterminds who were poised to kill thousands of people and do incalculable damage,” wrote cryptographer Bruce Schneier in a June 2007 column for Wired online titled “Portrait of the Modern Terrorist as an Idiot.” Schneier believes that terrorism remains a real threat, but he also believes that the danger posed by the various alleged and would-be terrorists who’ve been caught inside the United States since 9/11, many of them lured into plots by undercover law enforcement, has been greatly exaggerated. (I’ll have details about these sting operations in two later installments.) In The Looming Tower, Wright quotes Issam al-Turabi, a Bin Laden friend from his days in Sudan, thus: “I loved that man. … Unfortunately, his IQ was not that great.”

Are terrorists dumb?

It may be that Bin Laden’s family wealth and otherworldly dedication far outstrip his native intelligence. (Al-Zawahiri appears to be the brains of the operation.) But the real question isn’t whether terrorists are smart per se but whether they are rational. “Acts of terrorism almost never appear to accomplish anything politically significant,” prominent game theorist Thomas C. Schelling observed nearly two decades ago. Max Abrahms, a pre-doctoral fellow at Stanford’s Center for International Security and Cooperation, reaffirmed that conclusion in a 2006 paper for International Security titled, “Why Terrorism Does Not Work.” Abrahms researched 28 groups designated “foreign terrorist organizations” by the U.S. State Department since 2001, identifying among them a total of 42 objectives. The groups achieved those objectives only 7 percent of the time, Abrahms concluded, and the key variable for success was whether they targeted civilians. Groups that attacked civilian targets more often than military ones “systematically failed to achieve their policy objectives.”

In a 2008 follow-up essay, “What Terrorists Really Want,” Abrahms explained that terrorist groups are typically incapable of maintaining a consistent set of strategic goals, much less achieving them. Then why do they become terrorists? To “develop strong affective ties with fellow terrorists.” It’s fraternal bonds they want, not territory, nor influence, nor even, in most cases, to affirm religious beliefs. If a terrorist group’s demands tend to sound improvised, that’s because they are improvised; what really matters to its members—even its leaders—is that they are a band of brothers. Marc Sageman, a forensic psychiatrist and former Central Intelligence Agency case officer in Afghanistan, collected the biographies of 400 terrorists who’d targeted the United States. He found that fully 88 percent became terrorists not because they wanted to change the world but because they had “friendship/family bonds to the jihad.” Among the 400, Sageman found only four who had “any hint of a [psychological] disorder,” a lower incidence than in the general population. Think the Elks, only more lethal. Cut off from al-Qaida’s top leadership, they are plenty dangerous, but not nearly as task-oriented as we imagine them to be.

[Update, April 6: In a column published after this series (“Jihad Lite“) I consider whether a recently-discovered al-Qaida recruitment manual suggests the terror group is having difficulty attracting new members.]

Next: “The Near-Enemy Theory,” in which we’ll consider whether al-Qaida is too preoccupied with opportunities in Pakistan and Afghanistan to plot against the United States.