The deal that Iran and world powers are negotiating is said to include a freeze of part or all of Tehran's nuclear programme in return for the easing of sanctions, but many unknowns remain.
European Union foreign policy chief Catherine Ashton (L) and Iranian Foreign Minister Mohammad Javad Zarif attend a news conference at the end of the Iranian nuclear talks in Geneva November 10, 2013
Both sides failed to reach an agreement in marathon talks in Geneva that ended this weekend, and while they have decided to hold fresh negotiations on November 20, details of what these entail are few and far between as the seven countries involved stay firmly silent.
But the basic requirements of the so-called P5+1 group -- the five permanent members of the UN Security Council plus Germany -- and Iran are clear and some of the issues that were debated in Geneva are now in the public domain.
BASIC REQUIREMENTS
Western countries and Israel suspect that Iran is using its programme to develop nuclear weapons, which Tehran strenuously denies, saying it is for peaceful civilian purposes.
- World powers want Tehran to suspend the enrichment of uranium, which when enriched at 90 percent opens the doors to making nuclear weapons. Iran has 19,000 centrifuges which it uses to enrich uranium at 3.5 percent and 20 percent, a few technical steps away from weapons-grade. Western negotiators are mainly focused on stopping the latter.
- Just hours after the end of negotiations in Geneva, Iranian President Hassan Rouhani reiterated in Tehran that his country would retain its right to "enrichment on Iranian soil" whatever happens.
ISSUES BEING DEBATED
- The future of Iran's stock of uranium enriched at 20 percent, which now weighs 186 kilos (410 pounds). What to do with it? Destroy it? Put it under foreign control? Sell it?
- Tehran's construction of a new generation of centrifuges that will enrich uranium faster. Some experts say there are around 1,000 models of these new centrifuges.
- The Arak heavy water reactor in central Iran whose official function is to produce plutonium for medical research but could also be used for military purposes. France pressed hard on this issue at the talks. Experts say this reactor could be operational at the end of next year, at which point it would be harder to neutralise.
Inspectors from the International Atomic Energy Agency have occasional partial access to the plant. Media reports say Iran could accept not to activate its plutonium reactor.
- The future of underground nuclear facilities in Iran, and particularly the Fordo uranium enrichment site that the West wants neutralised.
EASING SANCTIONS
In exchange for Iranian concessions approved by the international community, some sanctions imposed by the United States and Europeans that have battered Iran's economy could be eased in a limited and reversible way.
Western countries would firstly prioritise the petrochemical and precious metals sectors. Some news reports point to a possible unblocking of Iranian assets in banks in other countries -- but not in the United States -- which represent tens of billions of dollars, experts say.