- January: IAEA confirms Iran is refining uranium to 20 percent fissile purity.
- February: U.N. inspectors end talks in Tehran without inspecting disputed military site at Parchin.
- April: Iranian President Mahmoud Ahmadinejad vows Iran will not surrender its nuclear rights.
- May: U.N. inspectors report they found find traces significantly upgraded uranium at an Iranian site.
- July: EU begins total ban on Iranian oil imports, US expands sanctions.
- September: IAEA demands access to Parchin, Iran calls EU sanctions "irresponsible."
December: IAEA says it makes progress in talks with Iran. US imposes more sanctions.
- January: Iran says it will speed up nuclear fuel work.
- February: Iran's supreme leader Ayatollah Ali Khamenei rejects direct nuclear talks with the U.S. Iran and world powers meet, agree to more talks.
- May: IAEA says Iran has expanded nuclear activity.
- September: Iranian President Hassan Rouhani says Iran will not seek weapons of mass destruction. Iran and world powers agree to resume nuclear talks.