[Esther]

The Planes
The widely accepted account that hijackers commandeered and crashed the four 9/11 planes is supported by reams of evidence, from cockpit recordings to forensics to the fact that crews and passengers never returned home. Nonetheless, conspiracy theorists seize on a handful of "facts" to argue a very different scenario: The jets that struck New York and Washington, D.C., weren't commercial planes, they say, but something else, perhaps refueling tankers or guided missiles. And the lack of military intervention? Theorists claim it proves the U.S. government instigated the assault or allowed it to occur in order to advance oil interests or a war agenda.

Source: http://www.popularmechanics.com/tech...42.html?page=2