You don't, because the iranians wouldn't just sit back and watch. They would immediately begin attacking any neighbour that's an ally of the US (basically, all the neighbours). Imagine how easily they would be able to destabalize Afghanistan and Iraq. How much economic damage they could do to the GCC with just a threat. For that, you would need ground forces. Unless ofcourse you are talking about eradication of Iranian life. In which case, that's not war at all, that's genocide.
They would not just ignore us and attack someone else. That notion is just dumb. The military option would be one minute their nuclear facilities would be gone. You don't need ground troops for that. If they decide to attack someone else for retaliation we would be on defense which is not as hard as invasion.
This is assuming they have no idea what's about to transpire. That's just ludicrous. Also, they have stated repeatedly that they would attack their neighbours if their nukes were hit - get a clue. They would immediately spill into Iraq/Afghanistan as well, and defending against that would undoubtedly cause an implosion from within those countries. If, as you're saying, the US went for the kill, the goal would become to hit the oil exporters and any US troops they can find. Also, keep in mind that Russia and China have always been very accomodating to Iran when the US is involved. Funny how that works huh? Again, yes Iran can be anihilated, but at this specific point in time, it would basically require the slow death of America in the process.... America can't bear the financial burden nor the ethical nightmare which would ensue. So if it makes you feel good, yes, the US can attack Iran (almost) remotely and demolish the country. Seeing as this would be suicide for the US, I don't see how that's special as tons of countries can do that. Nevermind that it would become open playground for Al Qaeda (great idea!!).
First off a tactical strike on their facilities is not wiping the country off the face of the earth. It is very small strikes in sparsely populated areas. Secondly, if they tried to go into other countries, ie MOVE, they would find it is very hard to do it without air support. Unless they are gonna send under cover donkeys or something as an invasion force.
