It is more useful in a cost/benifit way for Iran to have the apearance of brake out capasity with regards to nuke weapons with out declairing them selves a nuke armed state.  If they want the apearance of capasity they need large weapons sites that America seams very interested in but about which no one knows much for sure.  If they want weapons to use then buying black market Russian weapons and makeing apearances that they have no nuke capasity or interist gives them plausabal deniability when some city goes up.  Predition here is far less than perfect but I feel they want the statuse of being with in reach of the a domesticly produced weapon. 

 

I also think that a Iranian program will be far more like the South African one than the Israel one.