One thing that keeps going through my head, although I appreciate I'm probably a bit twisted in my thought processes, is what if the whole nuclear thing is a bit of a bait and switch?
Bear with me. Iran wants a weapon. Despite everybody on the global stage going "Woah there cowboy, not so fast" it builds several facilities, orders the ingredients, works on it, flaunts it's efforts, while intelligence is gathered by the concerned and ultimately triggers last night's events.
In their position, I'd be very quietly doing the dirty bomb deeds in a very very secret location while everyone focused on the "obvious" places. I'd be creating misdirection and obfuscation, just as the US did by having two lots of B2s in the air, one of which was essentially a decoy.
Look, i appreciate this isn't a Bond movie, and it's a serious matter, so I assume enough intelligence has been gathered to preclude the possibility. At least, I hope so.