Q&A: Iran nuclear issue
The International Atomic Energy Agency (IAEA) has said that medium-level uranium enrichment had begun at the Fordo plant near Qom in northern Iran.
Tehran has said it plans to carry out uranium enrichment there for purely peaceful purposes. The West argues Iran is building a nuclear weapons capacity.
In November 2011 the IAEA released its latest report on Iran's nuclear programme, presenting new evidence suggesting that Iran is secretly working to obtain a nuclear weapon. Iran has dismissed the claims as fictitious.
What does the IAEA report say?
The IAEA has long expressed concern about Iran's nuclear programme, but its latest report (November 2011) lays out the case in much greater detail than before.
Drawing on evidence provided by more than 10 member states as well as its own information, the IAEA said Iran had carried out activities "relevant to the development of a nuclear explosive device".
It said that some of these activities could only be used to develop nuclear weapons - though it did not say that Iran had mastered the process, nor how long it would take Iran to make a bomb.
The report documents alleged Iranian testing of explosives, experiments on detonating a nuclear weapon, and work on weaponisation - the processes by which a device might be adapted and hardened to fit into the nose-section of a missile.
There are some allegations that are listed openly for the first time, including the claim that Iran has used computer modelling on the behaviour of a nuclear device.
Previously, the IAEA complained that Tehran had not fully co-operated with its inspectors, though it did say that Iran had displayed "greater transparency" during an inspection visit in August 2011.
In March 2012, it was announced that Iran had agreed to take part in fresh six-party talks and allow IAEA inspectors to visit its key military research site at Parchin, under certain conditions.
The UN Security Council has ordered Iran to stop enrichment. Why?
Because the technology used to enrich uranium to the level needed for nuclear power can also be used to enrich it to the higher level needed for a nuclear explosion.
Iran hid an enrichment programme for 18 years, so the Security Council says that until Iran's peaceful intentions can be fully established, it should stop enrichment and other nuclear activities.
Under international law, an order from the Security Council is held to supersede rights granted by other international organisations. The Council has ordered sanctions under Article 41 of the UN Charter, which enables it to decide "what measures not involving the use of armed force are to be employed to give effect to its decisions". The Council has also called on Iran to ratify and implement an arrangement allowing more extensive inspections as a way of establishing confidence.
How does Iran justify its refusal to obey the Security Council resolutions?
Under the Nuclear Non-Proliferation Treaty (NPT), a signatory state has the right to enrich uranium to be used as fuel for civil nuclear power. Such states have to remain under inspection by the IAEA. Iran is under inspection, though not under the strictest rules allowed because it will not agree to them. Only those signatory states with nuclear weapons at the time of the treaty in 1968 are allowed to enrich to the higher level needed for a nuclear weapon.
Iran says it is simply doing what it is allowed to do under the treaty and intends to enrich only for power station fuel or other peaceful purposes. It says the UN resolutions are politically motivated. President Mahmoud Ahmadinejad has said: "The Iranian nation will not succumb to bullying, invasion and the violation of its rights."
What does Iran say about developing nuclear weapons?
It says it will not make a nuclear bomb. Following the IAEA report, President Ahmadinejad declared: "We do not need an atomic bomb. The Iranian nation is wise. It won't build two atomic bombs while you have 20,000 warheads."
Iran's Supreme Leader Ali Khamenei, who is reported to have issued a fatwa some time ago against nuclear weapons, has said: "We fundamentally reject nuclear weapons."
How soon could Iran make a nuclear bomb?
This would depend on Iran taking the decision to make a nuclear device and Iran says it will not do so. But experts believe that technically it could produce enough highly enriched uranium for a bomb within a few months. A US general said in April 2010 that Iran could still take several years after that to make a device. Former CIA chief Leon Panetta said in June 2010 that it could take two years. Israel's retired intelligence chief Meir Dagan has said it could take until 2015.
US Secretary of State Hillary Clinton said in January 2011 that sanctions had slowed down Iran's nuclear work. She also said that Iran had faced technical difficulties, possibly a reference to a computer virus said to have affected its centrifuge machinery. But in July 2011, Iran said it was installing new, faster centrifuges to speed progress in uranium enrichment. If successful, it could shorten the time needed to stockpile material that can have civilian as well as military purposes, if processed much further.
In theory Iran could leave the NPT with three months notice and it would then be free to do what it wanted. However, by doing that it would raise suspicions and leave itself open to attack. If, while remaining in the treaty, it enriched to nuclear weapons level or was found diverting material for a bomb in secret, it would lay itself open to the same risk.
But what about the US intelligence assessment issued on Iran in 2007?
The National Intelligence Estimate played down any early threat of an Iranian nuclear weapon. It assessed "with high confidence" that Iran did have a nuclear weapons programme until 2003, but this was discovered and Iran stopped it. The NIE added: "We do not know whether it currently intends to develop nuclear weapons."
However, Israel did not accept the conclusions and there was also doubt elsewhere. In 2008, the then director of US National Intelligence, Mike McConnell, appeared to backtrack, saying: "Tehran at a minimum is keeping the option open to develop nuclear weapons."
What sanctions has the UN imposed on Iran?
The UN has imposed four sets of sanctions, in Security Council resolutions 1737, 1747, 1803 and 1929.
These seek to make it more difficult for Iran to acquire equipment, technology and finance to support its nuclear activities. They ban the sale to Iran of materiel and technology related to nuclear enrichment and heavy-water activities and ballistic missile development, restrict dealings with certain Iranian banks and individuals, stop the sale of major arms systems to Iran (Russia has cancelled the sale of an anti-aircraft missile system) and allow some inspections of air and sea cargoes.
However, they do not stop the trade in oil and gas, the major source of Iran's income.
What about additional sanctions by the US and EU?
The US brought in restrictions on trade with Iran after the taking of American hostages in 1979, which it tightened in 1995, and in 2010 additionally targeted Iranian finances, shipping and the Revolutionary Guard.
In January 2012 the US imposed sanctions on Iran's central bank and against three oil companies that trade with Iran, including China's state-run Zhuhai Zhenrong Corp. The sanctions prevent the companies from receiving US export licences, US Export Import Bank financing or any loans over $10m from US institutions.
Later that month European Union foreign ministers formally adopted an oil embargo against Iran. This involves an immediate ban on all new oil contracts with Iran, while existing contracts will be honoured until 1 July 2012.
What are the chances of an attack on Iran?
Israeli Prime Minister Benjamin Netanyahu constantly stresses what he sees as a potential existential threat from Iran, so the possibility of an attack, by Israel at least, remains.
In March 2012, Mr Netanyahu said that time was running out to stop Iran developing a nuclear weapon, before any such programme became too advanced or went underground. He said he would never allow Israelis to "live in the shadow of annihilation".
Wikileaks revelations have shown that Gulf Arab states have urged the US to attack Iran.
American officials have stressed the instability that would result from any attack on Iran. They appear to be hoping that even if Iran continues to develop its nuclear expertise, it will not try to build a bomb.
US President Barack Obama said there was "still a window that allows for a diplomatic resolution". He warned that "loose talk of war" was playing into Iran's hands, but has stressed that all options remain open.
How does the nuclear plant at Bushehr fit in?
This reactor was started in the 1970s under the Shah but then put on hold until recently when the Russians finished it. The Russians will provide raw fuel and take away the spent fuel, which could potentially be used to make a plutonium-based nuclear bomb.
Bushehr is technically separate from the issue of enrichment. However, the US says that because Russia is providing the fuel, Iran does not need its own enrichment programme. Iran says that the reactor shows that it does have a civil nuclear power plan and that it needs to develop enrichment to serve this in the longer term.
What about fuel for the Tehran research reactor?
There is a small research reactor in Tehran making medical isotopes, installed by the Americans many years ago. This is running low on fuel, which has previously been provided from abroad. The US, Russia and France proposed taking Iran's stock of low-enriched (3.5%) uranium out of the country and return it as higher-enriched (20%) fuel rods. The idea was to get the low-enriched stock out of Iran and prevent it from being potentially used for a nuclear device.
On 17 May 2010 it was announced in Tehran that, after talks with Turkey and Brazil, Iran had agreed to ship low-enriched uranium to Turkey. However, Iran also said it would continue to enrich other uranium to 20%. Western governments rejected the deal and said it did not solve the basic enrichment issue.
What about Iran's enrichment plant at Qom?
A new and previously secret enrichment plant being built underground near Qom was revealed in 2009. The IAEA said it should have been declared much earlier and is demanding that construction stop. Iran says it broke no rules - there is a dispute about its obligations to the IAEA - and stated that it was constructing the plant in a mountain in order to safeguard its technology from an air attack.
Iran said the plant, known as the Fordo fuel enrichment plant, would enrich uranium up to 5% and would have 3,000 centrifuges.
In June 2011 Iran said the purpose of the plant was to enrich uranium to 20%, as well as carry out research and development.
In January 2012 the IAEA confirmed that Iran had started the production of uranium enriched up to 20% at the plant.
Don't existing nuclear powers have obligations to get rid of their weapons under the NPT?
Article VI commits them to "pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament". The nuclear powers claim they have done this by reducing their warheads, but critics say they have not really moved towards nuclear disarmament. Critics also argue that the US and UK have broken the treaty by transferring nuclear technology from one to another. The US and UK say that this is not covered by the NPT.
Doesn't Israel have a nuclear bomb?
Yes. Israel, however, is not a party to the NPT, so is not obliged to report to it. Neither are India or Pakistan, both of which have developed nuclear weapons. North Korea has left the treaty and has announced that it has acquired a nuclear weapons capacity.
On 18 September 2009, the IAEA called on Israel to join the NPT and open its nuclear facilities to inspection. The resolution said that the IAEA "expresses concern about the Israeli nuclear capabilities, and calls upon Israel to accede to the NPT and place all its nuclear facilities under comprehensive IAEA safeguards... "
Israel refuses to join the NPT or allow inspections. It is reckoned to have up to 400 warheads but refuses to confirm or deny this.