"Why would Iran want to battle with the U.S. when it is the U.S. that has the nuclear bomb? Thats a bit like David and Goliath wouldn't you say? "

You haven't seen the movie "The Mouse That Roared", have you? In that it clearly explains WHY the USA could NOT invade that tiny little country - the best they could do was 'offer to send them aid"....

:-)