TIMELINE On August 6, newlyelected Iranian President Hassan Rouhani says Tehran is ready for “serious” negotiations.

2002- 2004: UNDECLARED NUCLEAR SITES

After nuclear sites are uncovered in Natanz and Arak in central Iran in August 2002, Tehran agrees to undergo an inspection by the International Atomic Energy Agency ( IAEA). On October 21, 2003, following an unprecedented visit by foreign ministers from Britain, France and Germany, Iran suspends uranium enrichment activities.

2005- 2008: ENRICHMENT TO 3.5 PER CENT

On August 8, 2005, after the election of hardline President Mahmoud Ahmadinejad, Tehran resumes uranium enrichment. European nations break off negotiations. Iran, on April 11 says that it has enriched uranium to 3.5 per cent purity. It then rejects an offer from the permanent UN members plus Germany, dubbed P5+ 1, on a framework for talks. On December 23, 2006 the UN imposes the first of several rounds of sanctions on Iran’s trade in sensitive nuclear materials and technology. It is followed by the US and EU. On November 7, 2007 Iran says it has at least 3,000 centrifuges for enrichment, which in theory would allow it to produce enough enriched uranium for a nuclear bomb in less than a year.

2009- 2012: ENRICHMENT TO 20 PER CENT

In 2009, following the November election of United States President Barack Obama, world powers offer to resume negotiations with Tehran, which later declares major advances in its nuclear drive as Mr Ahmadinejad opens a uranium conversion facility on April 9 in Isfahan. On September 25, Western nations reveal the existence of a previously undeclared enrichment site inside a mountain in Fordo. On January 9, 2012, the IAEA says that Iran has started to enrich to 20 per cent at Fordo. On January 23, 2012, the European Union agrees to slap an embargo on Iranian oil exports and freezes the assets of Iran’s central bank.

2013: PRELIMINARY ACCORD