Joe: Although life is far from logical, where is the logic and motivation for the scenario you propose? Especially given the likely consequences for anyone pursuing your imagined course of action?
Iran is where shooting down 6 planes? Are the 6 planes overflying Iran? If so, why are they flying over Iran? (Even the US asks permission for overflights as it did of Iran during the Afghanistan war, although I think Iran said no.) Or is Iran in Iraq shooting down planes and attacking US troops? Does Iran invade Iraq just to mess with more trouble than it can possible afford? Does Iran have the military means (and any motivation) to do any of this and endure the likely consequences? Iran I suspect is in no shape to take on the US military or give the US an excuse for any sort of potential retaliation. And why would they? Rhetoric and politics aside, most regimes are not really suicidal. (Although Saddam makes one wonder...I figure if push comes to shove he won't go down with the ship but perhaps retire to a cosy life under an assumed name in some foreign clime...sort of a tyrant's protection plan.)
Also, in reference to Iran and other "terorist" states (like Syria, for example) do not underestimate the sub rosa dealmaking that has been going on since 911, public rhetoric notwithstanding. One never knows who the US has cut deals with.
As for North Korea, are you suggesting they just for the heck of it fire a missle at Japan and it accidently hits the US mainland?? That's quite a malfunction...good thing they gassed it up before it left home. Besides, why is NK attacking Japan? A missle attack on Japan achieves what? NK wants things from the rest of the world and is using the nuke card to try and get them. Blowing up the people it wants help from is kind of self defeating, although their rhetoric doesn't make much sense to me. As far as your scenario goes, NK seems just as likely as to declare war on Rhode Island.