Will the P-5 plus Germany seize the moment in their meeting with the Iranians at the Hotel de Ville in Geneva this week, present a united front and secure meaningful concessions on the nuclear program? Or will Iran offer just enough to ensure another round of meetings and buy time? Given the sound and fury generated by the latest disclosures about a new Iranian uranium enrichment facility near Qom and the almost comical defiance of Iran by going ahead with a flurry of missile tests, it is crunch time for President Obama and his national security team who are telling the world that a tough response will follow if Iran fails to come clean on its nuclear activities.

The problem is that the Iranian regime is under siege at home for reasons that have nothing to do with the nuclear issue. Thanks to the appalling treatment of their own citizens in the aftermath of the disputed June 12 presidential elections, the legitimacy of the leadership, especially Supreme Leader Ali Khamenei and President Mahmoud Ahmadinejad, has been seriously questioned, not only by activist reformers but by conservative members of the clerical establishment. For this reason, Khamenei and Ahmadinejad and their defense establishment cronies cannot appear weak either at home or abroad. They know their strong stance on the nuclear issue is one where they can count on support even from their domestic detractors. Under these circumstances, they are likely to offer a nugget here and a nugget there, hoping the gang of 6 will eventually fragment. This is probably a good strategy. It is likely that the United States, Britain and France will insist on a deadline by the end of the year for serious progress and will continue to coordinate plans for much tougher unilateral sanctions. They will assume that Russia and China will not support them. If Mrs. Merkel with her new victory and a stronger coalition can be persuaded that tough sanctions are in order, there is a great deal that Europe and the United States can do to further hurt the Iranian economy.

The question is whether this will persuade the Iranian leadership to bend. This won't happen; the leadership will use further sanctions to argue that they have a national security crisis and crack down even harder on dissenters. The reality is that there is no longer a grand bargain to be made with this particular Iranian regime. Those who draw a Nixon to China analogy must realize this would only hold if Iran were also threatened by another major power, such as Russia, but this is not the case. Some have suggested the U.S. offer Iran "security guaranties" as a way to get them to put their nuclear program under international control. This is a non-starter. The Mullahs would regard an American security guarantee as an insult. It would make them look weak. They have a strong sense of their own importance; they are the ones who should be offering security guarantees to their neighbors, not vice versa.

All in all, one can expect much gnashing of teeth in the coming weeks. Ultimately, this saga is going to play out in an unsatisfactory manner for all involved. Sooner or later there will be further cracks in Tehran and the rotten regime will collapse, but probably not before they have all the ingredients for a bomb. The test for the Obama administration and its allies is to be sophisticated and imaginative enough to hasten this event without precipitating yet another war in the Muslim world.

Geoffrey Kemp is the Director of Regional Strategic Programs at The Nixon Center.