OK here it goes...
Pat Buchananite Conspiracy Theory - Neocons acting on behalf of Israel did it to draw the US in.
Art Bell Conspiracy Theory - UFOs piloted by Illuminati did it to make money for world bankers to distract us from the impending asteroid collision kept secret by the man actually running the government...Elvis.
Michael Moronish Conspiracy Theory - Bush did it. Because he is friends with the Saudis and hey, you gonna eat that Twinkie?
Or, it's all just a diversion, they really want to kidnap Jack's daughter...
You laugh, but I read this morning in the WSJ that there are Turks who actually believes that the US knows that a giant asteroid is approaching Earth and will strike the US, and that we are trying to "take over" the Middle East so we can move there before it hits. It's called the "eighth planet" theory.
Nothing is too crazy for anti-Americans to believe.