On the side of one of Tehran�s traffic-clogged freeways, among giant murals portraying the heroes and martyrs of the Iranian revolution, a lurid billboard warns that the �nuclear issue is just an excuse� for America, Israel, Britain and other hostile powers to try to undermine the Islamic Republic�s independence and sovereignty. �If we give way on that, they will come up with many other excuses,� the text in Farsi reads.

Now that the marathon nuclear negotiations are finally approaching their end in Vienna on Tuesday, many Iranians still heed this suspicious message. Few, however, doubt that a deal will be done and sanctions will be eased, and that it will mark a new era in relations with the US and with the west, 36 years after Ayatollah Khomeini overthrew the shah and shook the Middle East. Many hope and believe that Iran�s economy, and perhaps its complex political system, will be deeply marked by the change.

�It is a big moment,� said Sadegh Zibakalam, a prominent reformist academic. �In years to come people will refer to this agreement as a landmark in modern Iranian history. It is of crucial importance that Iran has said: �OK, we are going to trust the west.� If we reach an agreement with the US � the Great Satan � on an issue that divided us for more than a decade, it will be a huge transformation.�

The impending deal looks like a triumph for Hassan Rouhani, elected president two years ago in place of the divisive Mahmoud Ahmadinejad, who ransacked government coffers to fund populist projects at home and outraged the world with his Holocaust denial. Still, everyone knows that Rouhani and his foreign minister, Javad Zarif, have the blessing of the supreme leader, Ayatollah Ali Khamenei, and that the regime desperately needs the agreement.

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