If anyone believes that our government couldn't or wouldn't have known about or allowed something like this to happen then you might want to look back at the first WTC bombing. The only reason why the bomb didn't do more damage and take hundreds if not thousands of lives is because there was a car parked in the spot they needed to be right next to the main support.
http://query.nytimes.com/gst/fullpag...=&pagewanted=1
As you can see it's documented in court records and even taped conversations of the FBI. They knew exactly what was going on. They could have provided a fake bomb but instead provided a real one.