The Pentagon no-plane theory holds that American Airlines Flight 77 did not strike the Pentagon on September 11, 2001, and that the building was instead hit by a missile, a smaller aircraft, or an internal explosion. The theory gained traction from the 2002 French book *L'Effroyable Imposture* by Thierry Meyssan and from early online photo collections noting that initial post-impact photographs did not prominently show aircraft debris. Extensive counter-evidence exists: the Flight 77 flight data recorder and cockpit voice recorder, DNA identification of passengers and crew, over 1,000 eyewitnesses along the aircraft's final approach, recovered aircraft debris (including engine parts), and the ASCE Pentagon Building Performance Report. No credible alternative trajectory or origin for a missile has ever been documented.