it would make them embrace THEIR OWN regime! they would unite and resist like hell, this is a no-brainer.
honestly, right now i cant really blame iran; think about it, their neighboring nations have been 'invaded' by the US...iraq and afghanistan. pakistan also has nukes. USA talking tough to them, clearly consideres them 'threatening'. if i were them, i would be after nukes for deterrence also, full speed ahead!
also its really isnt fair how we dont care if some nations have them and tell others that they cant.