The professed aim is to take out Iran's nuclear facilities, not to overthrow the government and occupy Iran. That's the professed aim. In regards to what would likely actually happen as a result, and how I suspect the neocons think they will be able to deal with it at that point, please read:
“If we want a war with a billion Muslims we can probably have one.” - Wes Clark
http://www.dailykos.com/story/2007/6/23/133937/363That's the title to a Kos Diary I wrote, it isn't an article by Clark, although he is quoted inside of it.