Some say the coordinated attacks on September 11, 2001 on the World Trade Center in New York City and on the Pentagon were an outside act of terror. Others contest that it was an inside job orchestrated by the American government.
After following the debate on and off for many years, this video seems to put some of questionable information together fairly well:
The arguments in both directions seem to suggest there are both truth and holes in each account of what supposedly happened.
I’m now of the mind that it likely was mostly an outside act of terror, but one that may have been allowed to happen in order to help make invading the Middle East more palatable to the public. There certainly is motive for both to have occurred.
Of course, I could be wrong.