This has been said a lot of times in lots of places. Did the US government know about the attacks prior to the attacks, and were they involved with the attacks?

  • 18
    Please restrict your question to a particular claim, we can't debunk every single conspiracy theory about 9/11 in one question.
    – Mad Scientist
    Apr 13, 2011 at 6:04
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    Is the claim that the President knew? Or that it was a black op, e.g. CIA? Please be specific.
    – Paul
    Apr 13, 2011 at 6:12
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    It's extremely unlikely to have been an inside job. I think it's likely that if this was the case, there'd be far more murmur than there is. The truth will always out, as it were. Apr 13, 2011 at 8:14
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    @TK, Lennart, picakhu: The alleged demolition of 7 World Trade Center was addressed in another question.
    – Patches
    Apr 14, 2011 at 3:58
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    @TKKocheran The WTC7 issue is addressed in another question as Patches noted. This discussion is somewhat off-topic here, and if you make such significant claims please provide an answer and cite your claims, don't just use the comments.
    – Mad Scientist
    Apr 14, 2011 at 8:20

1 Answer 1


Depends on what you mean by prior knowledge, and what you mean by the U.S. Government.

The 9/11 Commission Report highlights many failings by the FBI and the CIA and suggests that they had credible information about the attacks even though that they did not realise what they had at the time. This could be taken as them having prior knowledge even if they didn't know about it.

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    I call this the fourth category: aside from the "known knowns" and "known unknowns" and "unknown unknowns", you have the "unknown knowns" -- things you know but don't realize are relevant until after it's too late. Sep 30, 2015 at 7:25

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