2002

• Dec. 12-13: Satellite photographs broadcast by US television stations reveal the existence of nuclear sites at Arak, southwest of Tehran, and Natanz in the center of the country. The US media claims the facilities could have a military use. Iran agrees to an International Atomic Energy Agency (IAEA) inspection.

2003

• Feb. 9: Iranian President Mohammed Khatami announces uranium deposits have been discovered in Iran and Tehran is building two factories to convert the ore into nuclear fuel for power stations.
• Aug. 26: A confidential UN report reveals Iran has developed two kinds of enriched uranium not needed for peaceful energy production.
• Oct. 21: Tehran declares it will accept tightened inspections of its nuclear facilities and says it will not begin uranium enrichment – a process needed to produce a controlled reaction for nuclear fuel. In a very high concentration, enriched uranium is also used in the development of nuclear warheads.
• Nov. 10: An internal IAEA report states: "At the moment, there is no proof that Iran is creating nuclear weapons," a conclusion the United States disputes.
• Dec. 18: Tehran signs an additional protocol to the Nuclear Non-proliferation Treaty which agrees to unannounced inspections of nuclear facilities by the IAEA.

2004

• June 1: The IAEA claims to have found new traces of enriched uranium that exceed the levels necessary for civilian energy production.
• July 31: Iran admits to having resumed production of parts for centrifuges used for enriching uranium, but insists it has not actually resumed enrichment.
• Sept. 21: The Iranian government announces it has resumed large-scale conversion of uranium ore, a precursor process towards enrichment.
• Nov. 14: Iran accepts complete suspension of uranium enrichment activities, including uranium conversion while talks are held.
• Dec. 13: The so-called EU-3 made up of Britain, France and Germany begin negotiations with Iran. The European trio hopes to offer financial and technical assistance in exchange for guarantees that Iran will not stray from the proscribed course and begin nuclear enrichment.

2005

• Feb. 27: Iran and Russia sign a nuclear fuel accord that paves the way for the start-up of the Bushehr nuclear plant. Russia will fuel the reactor on condition that Iran sends back spent fuel.
• Aug. 5: Two days after taking office, President Mahmud Ahmadinejad rejects a broad compromise package with incentives put forth by the EU in the hopes of ending the escalating nuclear standoff.
• Aug. 8: Iran commences uranium conversion at its nuclear facility in Isfahan for the first time since November 2004. The EU breaks off its negotiations with Tehran.
• Aug. 11: IAEA board adopts a resolution demanding Iran halt nuclear fuel work but non-aligned nations express reservations.
• Sept. 2: IAEA releases a critical report saying Iran has continued sensitive nuclear fuel work and calls for full transparency.
• Sept. 20: Tehran threatens to resume uranium enrichment, block UN inspections and abandon the Non-Proliferation Treaty if it is referred to the UN Security Council.
• Sept. 24: With the exception of two abstentions from Russia and China, the IAEA passes a resolution reserving the right to send Iran's case to the UN Security Council.
• Nov. 11: In an attempt to resolve the mounting crisis, Russia offers to allow Iran to enrich uranium on its soil. The US and EU back the plan.

2006

• Jan. 3: Iran announces the resumption of nuclear research activities that were suspended for two years, provoking a call from the IAEA to continue the moratorium.
• Jan. 7 and 8: Russian-Iranian negotiations over Moscow's compromise solution break off. Tehran insists on enriching uranium on its own territory.
• Jan. 10: Iran removes the IAEA seals on equipment related to uranium enrichment at its nuclear facility in Nantanz. The international community condemns the move.
• Jan. 12: Britain, France and Germany say the time has come for the UN Security Council to become involved ad call for an emergency IAEA meeting. Iran threatens to halt cooperation with the IAEA if it goes to the Security Council.
• Jan. 27: US President George W. Bush voices support for the Russian proposal. Iran rejects it as "not sufficient" for its nuclear needs.
• Jan. 31: The five permanent Security Council members and Germany agree to a draft resolution asking the IAEA board of governors to inform the UN Security Council about Iran's nuclear program. References to punitive measures are removed from the draft at Russia's request.
• Feb. 2: Emergency session of the IAEA board of governors convenes. Russia and China drop earlier opposition and agree to support Western powers by voting for a resolution to refer Iran to the UN Security Council over its disputed nuclear activities.