I realize that this Onion article is somewhat of a spoof. But how many of us "ignorant" Americans were saying "I told you so!" on 9/11/01? How many of us "ignorant" Americans were thinking, years before, that something like a 9/11 was inevitable? And that it was made inevitable by America's weak foreign policy regarding terrorism particularly during the Clinton presidency, e.g., America's non-response to the USS Cole bombing.
Every other commentary is specious and full of hot air. I've seen them all, everything from "it was Reagan's fault for supporting the Afghan 'freedom fighters'" to "we shouldn't have had troops in Saudi Arabia in the first place." However, those things did not produce 9/11. 9/11 was produced by America's unwillingness to stop terrorism in its tracks in a proactive sense. 9/11 was produced by the US government sitting on its collective thumbs while terrorism only grew bolder and bolder in its attacks. Yes, the US certainly did bomb a few terrorist camps during the Clinton years - camps which were quickly rebuilt and put back into operation. And they were rebuilt because the terrorists, who were still alive to rebuild them, were not discouraged by any mere slap on the wrist.
9/11 happened because terrorists were left alive to carry out devious and destructive plots on the US mainland.