As he reminds us, even Hans Blix, the chief United Nations arms inspector before the war, believed that Saddam Hussein had hidden weapons of mass destruction. David Kay, who led the postwar Iraq Survey Group that found no evidence of weapons of mass destruction, went into his search expecting to find the opposite. In this sense, Bush and Blair were just along for the ride.

The myth of the super-weapons, once it gained currency, could not be dispelled. Saddam’s penchant for secrecy only made matters worse: “Every general knew he did not have the special weapons but thought his counterpart down the road did.” Even in the absence of a conspiracy, the widespread belief in Iraqi duplicity created a situation in which Saddam was unable to prove a negative: “The bar for intelligence that suggested there were no weapons was far higher than for any evidence of their existence.”

After the war, it turned out that British and U.S. spies had believed their own intelligence shaky, but thought the other’s conclusions were sufficient to bolster their analysis. Both agencies were undone partly by the sacred “control principle,” holding that if Country A gives information to Country B, Country B cannot share the details with Country C without the permission of Country A. …

Overall, Corera agrees with the conclusion of the British investigators: With a single exception, the intelligence wasn’t spun by the politicians. It was “simply wrong.” From the point of view of the spies, he points out, this realization is far more damaging. It means they didn’t do their jobs. And the political leaders, says Corera, “believed the intelligence they had been told about weapons of mass destruction in Iraq.”