After the UN's nuclear watchdog votes to censure Iran over its nuclear programme, BBC News Online looks at some of the key moments in the crisis.
Tehran has admitted producing plutonium, the IAEA says
September 2002: Russia begins preparations for a reactor worth $800m near Iran's south-western port of Bushehr. The plan at this stage is to have the plant up and running by the end of 2003.
December 2002: The US accuses Iran of seeking to develop a secret nuclear weapons programme and publishes satellite images of two nuclear sites under construction at Natanz and Arak.
February - May 2003: The UN's International Atomic Energy Agency (IAEA) conducts a series of inspections in Iran. The country confirms that there are sites at Natanz and Arak under construction, but insists that these - like Bushehr - are designed solely to provide fuel for future power plants.
16 June, 2003: IAEA head Mohammed ElBaradei states that inspections showed "Iran failed to report certain nuclear materials and activities" and urges "co-operative actions" on the part of Iran. However the report does not declare Iran in breach of the Non-Proliferation Treaty.
EU foreign ministers meanwhile call on Iran to allow tougher nuclear inspections.
19 June, 2003: White House spokesman Ari Fleischer refuses to rule out the "military option" in dealing with Iran.
July 2003: IAEA begins a fresh round of inspections in Iran.
September 2003: Washington says Iran is not complying with international non-proliferation accords but agrees to support a proposal from Britain, France and Germany to give the country until the end of October fully to disclose nuclear activities and allow surprise inspections.
13 October, 2003: Russia says it has delayed plans to start up a nuclear reactor in Iran by a year but stresses this is for technical reasons, not because of external political pressure.
19 October, 2003: Officials in Tehran hold negotiations with IAEA envoys on signing an agreement to allow tougher inspections of its nuclear facilities.
21 October, 2003: Iran's Foreign Minister Kamal Kharrazi promises "total transparency" over the country's nuclear programme during talks with his counterparts from Britain, France and Germany.
Shortly afterwards, a diplomat in Tehran says Iran has agreed to suspend the enrichment of uranium, and will sign an agreement allowing tougher UN inspections of its nuclear sites - two key demands of the IAEA.
24 October, 2003: Protest in Tehran against the decision to sign up to inspections.
31 October, 2003: The IAEA says Iran has submitted a "comprehensive" declaration on its nuclear programme.
10 November, 2003: Iran states again that it is suspending uranium enrichment and intends to allow tougher UN inspections of its nuclear facilities.
11 November, 2003: The IAEA says in a report that Iran has admitted that it has produced plutonium - a material that could be used in nuclear weapons, but adds there is no evidence that the country is trying to build an atomic bomb.
13 November, 2003: Washington dismisses the report, which it says it finds "impossible to believe". The UN stands by the report.
25 November, 2003: Britain, France and Germany reach an agreement with the US on a UN resolution to warn Iran over its nuclear activities.
26 November, 2003: The IAEA votes to pass the resolution censuring Iran, but stops short of recommending sanctions.