2002
August
Iranian exiles claim Tehran has built a vast uranium enrichment plant.
December
Satellite pictures confirm the development of a nuclear reactor at Bushehr on the Gulf coast of Iran. The US accuses Tehran of pursuing of weapons of mass destruction.
2003
October
Iran agrees to stop producing enriched uranium – required for nuclear weapons - but fails to provide any evidence that it has done so.
2004
November
Iran agrees to halt all enrichment activities during talks with EU states, but says it will resume enrichment in the future.
2005
April
Iran announces plans to resume enrichment.
August
Hardliner Mahmoud Ahmadinejad takes over as Iranian president, prompting a deterioration of relations with the west.
September
The International Atomic Energy Agency says Iran has resumed uranium conversion.
2006
February
The IAEA votes to report Iran to the UN security council and Tehran ends snap UN nuclear inspections.
December
The security council unanimously passes a resolution imposing sanctions on Iran over its nuclear enrichment.
2007
March
The security council agrees further sanctions.
October
The US steps up its sanctions on Iran, targeting the finances of Iran's Islamic Revolution Guards Corps and three state-owned banks.
December
A US intelligence assessment concludes that Iran stopped its nuclear weapons programme in 2003.
However, the National Intelligence Estimate assessment says Tehran has been continuing to enrich uranium.
2008
March
UN security council adopts third sanctions resolution.
May
The IAEA says it is seriously concerned about Iran's alleged research into nuclear warheads.
June
Shaul Mofaz, a deputy Israeli prime minister, says a strike on Iran's nuclear sites will be "unavoidable" if Tehran fails to halt its alleged weapons programme.
July
Iran test fires nine long- and medium-range missiles. Officials cite it as proof that the country can retaliate against any US or Israeli attack.
The US says it will send a senior diplomat to nuclear talks with Iran in a shift of policy towards engagement with Tehran.
August
Iran fails to respond to a deadline for it to agree to halt all nuclear activities in exchange for a freeze on further UN sanctions.
It later announces it has stepped up its uranium enrichment programme.
September
In his valedictory speech to the UN general assembly George Bush once more highlights the threat posed by Iran's nuclear programme.