On a more general note I do believe that the Iranian regime knows, at least for the moment, that the US will not engage into a new invasion and especially not of Iran.  That would mean disaster both economically and militarily for the US.  The hardliner stand of the Iranian regime is pointing to the fact that they have calculated along those lines and thus can act so defiantly.  This is both a propaganda stunt and a political strategy stunt from the Iranians in order to rally support for the hardliner stands among the Iranian population and a political test to see how far the Western countries are willing to go in such a showdown.  

The rallying of the population to the hardliners stands seems so far to have failed.  Even if the majority of the population are for the nuclear program, there are signs that they are getting tired of the hardliner stands and have come to rather like the reformists way. The rather meagre support the violent demonstrations in Teheran had during the cartoon incident, point towards such a conclusion, the demonstrators, consisting of mostly young conservative males and members of the Pasdaran, and being only in the hundreds/thousands(?).  

Concerning their political strategy it also seems as if this was a miscalculation, with the hardliners threatening to walk out of possible negotiations if Iran was referred to the UNSC by the IAEA.  The tough rhetoric backfired and the UN process started.  Still, the Iranians keep sending mixed signals, defiance in order to save face and being willing to still negotiate with the Russians in order to keep the only option left open and not politically humiliating the Russians.    

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