Iran's president Mahmoud Ahmedinejad has just called the Nazi Holocaust a "myth".
That means, that the priests in power in Tehran has just placed themselves in the same category as neo-nazis and the like. That is what everybody should know, and take extremely serious. If the current Iranian regime gets nuclear weapons, you are dealing with nukes controlled by nazi-like people. This should of course be prevented, by all effective means.
An invasion by US is out of the question, if it resembles the invasion of Iraq. Israeli air-strikes might very well trigger ww3. So what is the solution?
As far as I know, Iran would need probably 5-10 years to develop nuclear capacity. At the same time, the regime does not seem to be totally stable, with a growing opposition - including priests and clerics no longer supporting the concept of "Islamic State". So the only possibility might be to support this opposition in various ways.
Today they are voting in Iraq, but the outcome of this is very unclear for the moment, I think. If you try to imagine a stable, reasonably democratic Iraq, which is also "Islamic", but in another way than Iran - one could hope that this new model/system could be exported to Iran?