If the US had an educated administration not composed by lap dogs they would've known that attacking Iran was going to be a terrible idea.
Saddam did the same mistake in 1980.
He thought that the Iranian Kurds, the political opponents, the Iranian Arabs, civilians were going to raise against the regime.
None of this happened. None. In fact, hundreds of thousands of people, even kids, rallied around the banner. There are documented stories of 13 year olds, jumping on barbed wire to use their bodies as bridges for infantry. Disgusting, yet telling of the fact that the Persians will do everything to defend their land even if they don't like its leadership.
It's very difficult to convince people you're bombing left that you're helping them get rid of a regime (which, you never know for sure how popular or unpopular it is).
Iranians, yet again, are rallying around the flag for what is effectively a foreign aggression.