Se lo è chiesto Michael A. Sheehan in un recente convegno:

 With the benefit of more than a decade of hindsight, America may have misjudged the true threat posed by al-Qaeda in the immediate aftermath of the 2001 terrorist attacks, a top Pentagon official said Tuesday.
“Al-Qaida wasn’t as good as we thought they were on 9/11,” said Michael A. Sheehan, the assistant secretary of defense for special operations and low intensity conflict.
“Quite frankly, we, the American people, were asleep at the switch, the U.S. government, prior to 9/11. So an organization that wasn’t that good looked really great on 9/11,” Sheehan told a room full of special operators in Washington who were attending an annual Special Operations, Low Intensity Conflict Planning Conference.
“Everyone looked to the skies every day after 9/11 and said, ‘When is the next attack?’ And it didn’t come, partly because al-Qaida wasn’t that capable. They didn’t have other units here in the U.S. … Really, they didn’t have the capability to conduct a second attack.”
The true limitations of al-Qaida are one of two key reasons that America has not suffered a major terrorist attack since 2001.
“The other reason is that we actually responded … and crushed al-Qaida immediately after 9/11, and continually for the last 10 years,” Sheehan said. “We are better than we often give ourselves credit for. We have a very polarized political system and it’s very difficult for anybody to actually give credit or receive credit for how good we are.”
Sheehan pointed to the “brilliant operation” in October 2001 that ousted the Taliban from power in Afghanistan, a combination of special operations, intelligence agencies and Air Force capabilities.
He said that operation was a “precursor” to many successful operations since.