My mother recently asked, “Honey, what exactly makes your book different than any other 9/11 book?” Nothing like a zinger from your own mother to get you thinking.

So here are my five most important findings.

Finding #1: Organizations, not individuals, were the root cause of failure
Most 9/11 books have focused on the personal drama of failure. It’s all about individuals, whose hair was one fire, who was sitting “at the center of the storm,” and the political battles they won and lost. But I’ve come to believe this emphasis is misplaced. And it’s dangerous because it suggests that a few pink slips can fix what’s broken in U.S. intelligence.

The real problem is worse. It’s called bureaucracy. Why were 19 terrorists able to kill 3,000 Americans? Because U.S. intelligence agencies never adapted to the end of the Cold War and the rise of a new enemy. In particular, the CIA and FBI were —and still are—hobbled by organizational structures, cultures, and professional incentive systems that didn’t give them a fighting chance against al Qaeda.

Consider this: Nineteen days before 9/11, the FBI began a manhunt for Khalid al-Mihdhar and Nawaf al-Hazmi, two of the hijackers who flew American Airlines 77 into the Pentagon. But the search was given to just one of the FBI’s 56 U.S. field offices, labeled “routine,” the lowest priority level, and handed to an agent who had just finished his rookie year. This wasn’t a screw-up. It was the natural product of the FBI’s longstanding organizational weaknesses.

The Bureau’s structure was so decentralized, insiders joked that the FBI consisted of “56 field offices with a headquarters attached.” In the FBI system, every case was assigned to one lead office for investigation. This made sense during the Cold War, when the dominant mission was responding to local criminal priorities. But it ensured that what should have been a nation-wide terrorist manhunt was instead the focus of a few people. What’s more, the investigation went to the bottom of the pile because FBI culture had always prized catching criminals and investigating past crimes more than finding potential terrorists and preventing future disasters. And it was assigned to a junior agent because of his inexperience, not despite it. In an organization where convictions made careers, finding potential terrorists went to one of the office's least seasoned investigators because it was one of the least desirable jobs.

Finding #2: There were more missed opportunities than previously known
Several of the agonizing missteps and missed clues before 9/11 have been well publicized. The 9/11 Commission lists ten on pp. 355-56. I found several more buried in declassified documents and testimony before Congress and the Commission, for a grand total of 23 (11 missed by the CIA, 12 by the FBI). The recently declassified summary of the CIA’s own 9/11 review suggests there may be even more.

A couple of my favorites:

The FBI’s July 2001 Phoenix memo, which warned that bin Laden might be sending terrorists to train in U.S. flight schools, listed a primary subject who turned out to be an associate of hijacker Hani Hanjour. But the subject was never successfully investigated by the FBI before 9/11. Why? Because as luck would have it, he was outside the U.S. when the FBI tried to find him—and FBI procedures strongly encouraged special agents to close investigations once subjects were determined to have left the country. Intelligence officials now believe the subject may have reconnected with Hanjour in the summer of 2001 as part of the 9/11 operation.

Twice in the summer of 2001, FBI Acting Director Tom Pickard called the heads of all FBI field offices to warn them about the heightened threat of terrorist attacks. This was a golden opportunity to pulse the system and put pieces together. But instead of asking field offices for information or analysis about potential plots, Pickard directed them to have their evidence teams ready to deploy. Steeped in Bureau culture, the nation’s top cop was focused on responding to an attack, not preventing one.

Finding #3: Hindsight ain’t so biased.
Intelligence officials often complain – with good reason—about the danger of hindsight bias. Warning signs often seem obvious only after disaster strikes.

In this case, however, the historical record shows that BEFORE 9/11, intelligence officials and policymakers understood the terrorist threat and the dire need for intelligence reform, but failed to get the changes they believed were needed. Terrorism, for example, made the CIA’s top threat list every year starting in 1994, when the assessments were first made public. Between 1991 and 2001, a dozen major unclassified reports issued 340 intelligence reform recommendations. I spent two years tracking what happened to them, and found that almost none were implemented before 9/11. The vast majority – 268 to be exact—produced no action at all. In retrospect, these recommendations were right on target. Eighty-four percent focused on the same four crucial deficiencies (information sharing, coordination, prioritizing missions, and human intelligence) that the 9/11 Commission and Congressional Intelligence Committees highlighted after the attacks.

Finding #4: Intelligence reform isn’t impossible, but it’s close
Intelligence reform is languishing now for the same reasons it failed before 9/11: no organization changes easily from within; reform is a political loser for the president because it requires battling his own defense department; and our fragmented federal government makes legislative reform even more difficult. As 9/11 Commission Executive Director Philip Zelikow said, “the most powerful interest group in Washington is the status quo.”

Finding #5: Conspiracy theories are alive, well, and baseless
9/11 conspiracy theory books sell. A lot. And I get conspiracy theory questions nearly every time I lecture about my book. So for the record: I found not a shred of evidence supporting any kind of Bush administration conspiracy. Apparently, however, that may make me part of the cover-up cabal.