A couple of points. First, during the Cold War there was a VERY limited number of "the usual suspects". If the US got nuked, there was an infinitesimally small chance that it was Britain or France that did it and the USSR was pretty much the only other power with the capability to deliver such a weapon.
Right now, in theory, there's fissile material from the US, USSR, GB, France, China, India, Pakistan, probably N. Korea and Israel with Iran apparently on the verge. It's known that some of these states (Pakistan) have supplied technology and some may have possibly sold fissile material to other states.
I think the idea that either Israel or the US would start slinging nukes in 5 minutes is completely unbelievable. For a response of this kind, there will have to be a target that has been proven "guilty" with little doubt.
Second, the idea that Congress was persuaded to give Bush authority to invade Iraq base on Iraqi involvement in 9/11 is ludicrous. The case made in the UN and in our Congress was that Iraq had defied UN resolutions and was in possession of WMD's. THAT is how the war was "sold", not on the basis of Iraqi involvement in 9/111.
Are there parts of the citizenry that believe Iraq played a role in 9/11? Sure. But they didn't make the decision to go to war, Congress did.
Are you saying Congress believed Iraq had a role in 9/11?