| 1967 | US provided the Shah of Iran with a 5-megawatt research reactor, which used weapons-grade fuel. |
| 1979 | Ayatollah Khomeini replaced the Shah and closed the Iranian nuclear programme. |
| 1984 | During the Iran-Iraq war, Khomeini reinstated the nuclear programme. |
| 1987 | The research reactor was converted from 93 per cent enriched uranium fuel to just under 20 per cent (as now). |
| 2002 | Iran's secret nuclear programme, including the enrichment plant at Natanz and the heavy-water plant at Arak, was revealed by a rebel group. |
| 2005 | Mahmoud Ahmadinejad was elected president. |
| 2006 | Enrichment restarted at Natanz. Arak plant reopened. First round of UN sanctions approved. |
| 2009 | Western powers announced discovery of underground enrichment plant at Fordow. |
| 2010 | Stuxnet computer worm hit Iranian centrifuges. Targetted assaults on Iranian nuclear scientists. |
| 2012 | EU oil embargo on Iran took effect. |
| 2013 | Hassan Rouhani was elected president. Interim Geneva accord limited Iran's nuclear programme in exchange for partial relief from sanctions. |