Iran's nuclear ambitions

1967: Iran's first nuclear reactor begins operation.

1970: Iran's parliament ratifies nuclear nonproliferation treaty.

1979: The Iranian revolution results in a severing of U.S.-Iranian ties.

1984: U.S. adds Iran to its list of state sponsors of terrorism.

1992: Congress prohibits transfer of technology that might aid Iran's weapons proliferation.

1996: Congress penalizes U.S. investments topping $20 million per year in Iran's energy sector.

2003: International Atomic Energy Agency calls for Iran to suspend all uranium enrichment. Iran agrees to do so.

2005: Russia agrees to provide fuel for an Iranian reactor; Iran promises to return spent nuclear fuel to Russia. IAEA finds Iran in noncompliance.

2006: IAEA asks United Nations Security Council to force Iran to suspend enrichment activities and cooperate with investigators. Iran announces that it has enriched uranium for the first time.

2007: IAEA, Iran agree on plan for Iran to share details about its nuclear activities. U.S. says Iran ended nuclear weapons program in 2003.

2009: Iran announces first satellite launch, raising concerns about its ballistic missile potential. U.S. agrees to participate in talks with Iran. Western officials accuse Iran of building a secret, second uranium-enrichment facility.

2010: U.N., Congress expand sanctions against Iran.

2012: Talks with Iran begin. Israeli Prime Minister Benjamin Netanyahu draws a "red line" for an attack on Iran if it develops a nuclear bomb.

2013: Talks continue and details of an agreement emerge.

2014: Negotiations on comprehensive agreement extended until 2015.