Iran also knows that Americans don't want high gas prices so they targeted Americans' wallets from the outset. If even a half-assed invasion attempt existed that so much as involved a single dock being damaged, the psychological damage to America would be intense. America hasn't really been invading in, what, 2 centuries? War is a thing that happens "over there", never at home. It's easy to dissociate and pretend it doesn't affect you. Once people realize they've poked a bear, regret sinks in fast.