Factbox - A guide to nuclear talks between Iran and six major powers
By Louis Charbonneau VIENNA (Reuters) - Iran and six world powers - the United States, Britain, France, Germany, Russia and China - are in what may be the final phase of negotiations aimed at securing a deal on sanctions relief in exchange for limits on Iranian nuclear activities. The six powers have a June 30 deadline but diplomats close to the talks expect that to slip. BACKGROUND The nuclear standoff between Iran and the West goes back to at least 2002, when a group of exiles revealed undeclared nuclear facilities in Iran. The International Atomic Energy Agency (IAEA) later confirmed that they were a uranium enrichment plant at Natanz and a heavy-water production plant at Arak. Iran says its nuclear programme is peaceful but Western intelligence agencies are convinced Iran had a nuclear arms programme that went dormant, possibly as far back as 2003. In 2003, Britain, France and Germany began an inconclusive effort to persuade Iran to suspend uranium enrichment, a process that can produce fissile material, the key component for an atomic bomb. In 2006, the United States dropped its opposition to engagement with Iran and joined the three European powers, along with Russia and China, a group known both as the "P5+1" and the "E3+3". That year, the United Nations Security Council imposed sanctions on Iran for refusing to suspend enrichment and other sensitive nuclear work. This was followed by more draconian restrictions imposed by the United Nations, the United States and the European Union. Negotiations stalled until Iranian President Hassan Rouhani's 2013 election. In November 2013, Iran and the six powers reached an interim deal that gave Tehran limited sanctions relief in exchange for some curbs on its most sensitive nuclear work. It was meant to buy time to negotiate a final, long-term pact. The interim deal has been extended twice, in July and November last year. On April 2, Iran and the six agreed on the parameters for a final, long-term deal in Lausanne, Switzerland. The deadline for an agreement is June 30, though negotiations are expected to run into July. REGIONAL CONTEXT Israel and Saudi Arabia, Iran's main regional foes, are sceptical of the negotiations and oppose a deal. Iran has become more assertive in the Middle East, supporting proxies in Yemen, Syria and Lebanon. Analysts believe that if Iran secures sanctions relief it will boost its confidence as a regional power and improve its flagging economy. Sunni-ruled Arab states fear it will give Shi'ite Iran more resources to fan regional conflicts. BREAKOUT TIME The point of an agreement is to reduce Iran's nuclear "breakout" time - the time needed to produce enough highly enriched uranium or bomb-grade plutonium for a single weapon - to at least one year from the current estimate of 2-3 months. U.S. CONGRESSIONAL REVIEW Under a law pushed by Republicans sceptical of negotiations with Iran and ultimately backed by the White House, President Barack Obama's administration will have to submit any agreement to Congress for a 30-day review period during which Obama will refrain from suspending sanctions. If Congress receives the text of a deal after July 9, that review period will be doubled to 60 days, which officials close to the talks worry is too long. STICKING POINTS SANCTIONS RELIEF - Sanctions will be suspended and later terminated based on verification of Iran's compliance with the agreement. There are disputes about the timing. Iran's Supreme Leader Ayatollah Ali Khamenei wants sanctions lifted as soon as there is a deal, though Western powers say they will be suspended gradually, in return for steps by Iran to constrain its nuclear programme. U.N. nuclear-related sanctions will be removed on the basis of a Security Council resolution. Those sanctions will be restored under a "snapback" plan if Iran violates the deal CENTRIFUGES - Machines that purify uranium for use in nuclear power plants or weapons. In Lausanne, Iran agreed to reduce its roughly 19,000 centrifuges installed at two enrichment facilities - Natanz and Fordow - to 6,104. All 6,104 centrifuges are to be first-generation IR-1s. Iran also agreed to not enrich uranium beyond 3.67 percent for at least 15 years - well below the 90 percent needed for weapons. There would be 5,060 centrifuges at Natanz and 1,044 at Fordow. Iran would be prevented from installing further centrifuges for 15 years. RESEARCH AND DEVELOPMENT - Iran wants to continue research and development (R&D) into uranium enrichment. According to a French fact sheet, Tehran would be allowed a "gradual and precisely defined increase in (enrichment) capacity between the tenth and thirteenth years with the introduction of advanced IR-2 and IR-4 centrifuges." According to the United States, the two sides agreed in Lausanne that Iran would be allowed to conduct limited R&D using advanced centrifuges, pending the approval of the other powers. Critics of a possible deal are opposed to Iran acquiring further nuclear expertise. MONITORING AND VERIFICATION - Iran and the six have yet to agree on a detailed plan for monitoring and verifying the implementation of the deal. The biggest sticking point is access for International Atomic Energy Agency inspectors to Iranian military sites and nuclear scientists. Khamenei has said both would be off-limits, though Western officials say Iranian negotiators have indicated access would be possible. DURATION - If there is a deal, Iran's uranium enrichment programme will be subject to limitations for a period of 15 years. After 10 years, some of those would be eased. Khamenei has said Iran would not limit its nuclear activity for as long as 10 years, even though Tehran agreed to that in Lausanne. URANIUM STOCKPILE - Iran is to reduce its current stockpile of about 8,700 kg of low-enriched uranium (LEU) to 300 kg of 3.67 percent LEU for 15 years. Iran had previously said it was unwilling to ship LEU out of the country and, instead, wants to convert much of the LEU to a less proliferation-risky form. Officials close to the talks say this issue remains unresolved. Olli Heinonen, a nuclear expert and former IAEA deputy chief, says the one-year breakout target cannot be achieved without shipping much of the material out of the country. ARAK HEAVY-WATER REACTOR - Iran agreed to rebuild the Arak heavy-water research reactor based on a design agreed by the six. The idea is that it will focus on peaceful research and the production of medical isotopes. Officials say the redesign has yet to be agreed. POSSIBLE MILITARY DIMENSIONS (PMD) - Under the Lausanne agreement, Iran must answer queries the IAEA has about past activities that may have been related to atomic weapons research. Iran has been stonewalling the IAEA probe. Western officials have said that some sanctions relief under a possible nuclear deal would depend on resolving those queries. U.S. and other Western officials said U.S. Secretary of State John Kerry called Iranian Foreign Minister Mohammad Javad Zarif and told him that PMD questions must be resolved. (Compiled by Louis Charbonneau; Editing by Digby Lidstone)
