Conspiracy Encyclopedia

9/11 conspiracy theories allege that the September 11 attacks in 2001 were either intentionally allowed to happen or were a false flag operation orchestrated by elements within the United States government. The most prominent claim is that the collapse of the World Trade Center and 7 World Trade Center were the result of a controlled demolition rather than structural weakening due to fire. Another prominent claim is that the Pentagon was hit by a missile launched by elements from inside the U.S. government or that a commercial airliner was allowed to do so via an effective stand down of the American military. The common prescribed motives are the use of the attacks to justify the invasion of Afghanistan and Iraq, to facilitate increased military spending, and to restrict domestic civil liberties.

Published reports and articles by the U.S. National Institute of Standards and Technology, Popular Mechanics and mainstream media have rejected the 9/11 conspiracy theories. Civil engineers state that the impacts of jet aircraft at high speeds in combination with subsequent fires, rather than controlled demolition, led to the collapse of the Twin Towers and WTC 7.

• History
• Mainstream account
• Variants
• Main Theories
  • Foreknowledge
  • World Trade Center collapse
  • The Pentagon
  • Flight 93
  • Hijackers
  • Phone calls
  • Jewish and Israeli involvement
• Other Theories
  • Cover-up allegations
  • Foreign governments
  • No plane theories
  • Reptilian shape-shifting aliens
  • International Global Drug Industry cartel
• Motives
• Media reaction
• Criticism