The red line for Western negotiators:
And if Iran is going to maintain the right to enrich uranium to even low levels, as it continues to insists it must, the West would surely demand highly intrusive inspections — far more than Iran has tolerated in the past. How these matters are resolved will go far in deciding the success or failure of the talks
Iran starts from a position of strength:
Two important elements overshadow the upcoming negotiations: power and culture. Currently, Iran clearly has a better bargaining position, since it has more valid alternatives. The West’s alternatives to an agreement are limited to either strengthening sanctions or military action. Iran’s alternative to an agreement – to continue the enrichment process – seems today more realistic, achievable and “less costly” than the alternatives of the other side. Via Haaretz
But as Brett Stephens notes in the WSJ, showing strength is, in itself, an important tactic to achieve a deal with Iran. But then again, these past relationships have been filled with misunderstandings and difficulties, important details for upcoming negotiations.