Would the Bush administration have stopped the 9/11 attacks had it taken the threat more seriously? Possibly. On August 3, a Saudi named Mohamed al-Kahtani tried to enter the United States in Orlando, Florida, allegedly to participate in the 9/11 plot. He was sent back home by a customs official whose only concern was that he might become an illegal immigrant. On August 16, FBI and INS agents in Minnesota arrested another potential hijacker, Zacarias Moussaoui, after being tipped off by his flight instructor. But despite numerous requests, they were denied permission to search his apartment or laptop. These incidents “might have exposed the” 9/11 plot, writes Eichenwald, “had the government been on high alert.”

Clarke makes the same argument. When the Clinton administration received word of a potential attack in December 1999, he notes, President Clinton ordered his national security advisor to “hold daily meetings with the attorney-general, the CIA, FBI.” As a result, the leaders of those agencies instructed their “field offices to find out everything they can find. It becomes the number one priority of those agencies.” This vigilance, Clarke suggests, contributed to the arrest on December 14 of an Algerian named Ahmed Ressam, who was arriving from Canada with the aim of detonating a bomb at Los Angeles International Airport.

The Bush administration could have done similar in 2001. “Buried in the FBI and CIA,” Clarke notes, “there was information about two of these al-Qaida terrorists who turned out to be hijackers [Khalid al-Mihdhar and Nawaf al-Hazmi]. The leadership of the FBI didn’t know that, but if the leadership had to report on a daily basis … to the White House, he would have shaken the trees and he would have found out those two guys were there.”

Would that have foiled the 9/11 attacks? “There was a chance,” Clarke argues, but top Bush officials “didn’t take it.”