You forgot reason #4: If they nuked us, who the hell would by their stuff? Who would pay off (like we ever could) their US bonds?
You don't go around beating up your best customer, plus they would wreck the collateral that is backing the bonds ... the USA itself.
Oh, you mean the oil, natural gas, and coal that Kurinton and 0bama have been putting off-limits--that'll still be at least somewhat accessible, irrespective of what happened above-ground in such areas.
HF