Several comments about my 9/11 book SPYING BLIND raise a crucial question: can I really talk about the causes of 9/11 without commmitting hindsight bias? The answer is you bet. 340 reasons explain why.

I was deeply worried about this question, so spent two years tracking what happened to every unclassified intelligence reform recommendation from 1991 to 2001. I found that a dozen unclassified studies examined the CIA, FBI, intelligence overall, and US counterterrorism capabilities during the decade. These weren't obscure little groups, but high profile blue ribbon commissions, government studies (Clinton's reinventing government initiative, the FBI's own strategic plan, to name just 2), and nonpartisan think tank task forces sponsored by places such as the Council on Foreign Relations. Together, these studies issued 340 recommendations for reforming intelligence agencies. But almost none of the suggested fixes were implemented before 9/11. Most -- 268 to be exact, or 79% of the total-- produced no action at all. Zip. Nada. Nothing. Only 35 were fully implemented, and these were mostly "study the problem more" suggestions. Here's the kicker: in retrospect, these pre-9/11 reform recommendations were right on target: 84% focused on just 4 key problems:

1. Information sharing 2. The inability of the CIA, FBI, and other intel agencies to work as a unified team 3. Weaknesses in setting priorities 4. Poor human intelligence.

Sound familiar? These are the same deficiencies the 9/11 Commission and Congressional intellgence committees' Joint Inquiry into 9/11 identified as crucial weaknesses that left us vulnerable.

There's more. Much more. Hindsight bias is all about the historical record. And in this case, the historical record is clear: the CIA Director told Congress publicly that terrorism ranked among the top threats to U.S. national security every year from 1994 (when the threat assessment was first made public) to 2001; President Clinton mentioned terrorism in every State of the Union address from 1994 on; in 1999, Secretary of Defense Cohen even wrote an op-ed to an obscure little paper called the Washington Post in which he explicitly predicted a terrorist attack on American soil. That's just a preview of the highlight reel.

It's a smart and fair question to ask whether we really could have seen it coming before disaster struck. But evidence suggests that years before 9/11, intelligence officials and elected lawmakers were aware of the al Qaeda threat, and understood the imperative for intelligence reform. But they were unable to get the fixes they believed were vitally necessary. Sometimes hindsight isn't as biased as it appears.