Maybe the US military commanders, generals and Pentagon knew this but the civilian leadership at the top chose to completely ignore it and can't really articulate a plan or what the plan ever was.
This conflict was a long time coming: Trump claimed Biden or Obama will start a war in Iran and that is why they are weak presidents. Trump sees himself as a peacemaker (flying in to negotiate deals with TH and KH, negotiating Ukraine war, etc).
I think there is more going on to cause Trump drastically change his self-image.
I don't think this is a Trump administration driven decision.
All reports are saying the US generals were against this. And a UD senator (Graham I think) just admitted he lobbied trump for the war, comparing him to Roosevelt, and coached Netanyahou on how to lobby trump. Just look at the article:
I think there is more going on to cause Trump drastically change his self-image.
I don't think this is a Trump administration driven decision.