The International Atomic Energy Agency has confirmed that Iran has scaled down its nuclear program, paving the way to end Western sanctions under Tehran's deal with world powers.
Since the announcement, the European Union and the United States have announced they are lifting economic sanctions that have long isolated Iran as a long-sought deal to settle the conflict over Tehran's nuclear program comes into effect.
TIMELINE OF US-IRAN RELATIONS SINCE 1953 COUP:
1953 - CIA helps orchestrate overthrow of Prime Minister Mohammed Mossadegh, restoring Shah Mohammed Reza Pahlavi to power.
1957 - US and Iran sign civil nuclear co-operation deal.
1967 - US provides Iran with the Tehran Research Reactor, a 5-megawatt nuclear reactor along with weapons-grade 93 per cent enriched uranium fuel.
1968 - Iran signs the Nuclear Non-Proliferation Treaty which permits it to have a civil nuclear program in return for a commitment not to acquire nuclear weapons.
1979 - Iran's Islamic Revolution forces US-backed Shah to flee, Ayatollah Ruhollah Khomeini returns from exile and becomes supreme religious guide. Fundamentalist students demanding Washington hand over the Shah for trial seize US embassy in Tehran on November 4 and hold staff hostage for 444 days.
1980 - US cuts diplomatic ties with Iran, seizes Iranian assets and bans most trade with it. US hostage rescue mission ordered by President Jimmy Carter fails when helicopter crashes in sandstorm and eight US servicemen die.
1981 - Iran releases US hostages minutes after Carter steps down and Ronald Reagan is inaugurated as president.
1984 - US lists Iran as a state sponsor of terrorism.
1986 - Reagan reveals secret arms deal with Tehran in violation of US arms embargo. Money from the sales secretly passed to anti-communist guerrillas in Nicaragua.
1988 - US warship Vincennes mistakenly shoots down Iranian passenger plane over the Gulf, killing all 290 aboard.
2002 - President George W. Bush declares Iran, Iraq, North Korea an "axis of evil". US officials accuse Tehran of operating secret nuclear weapons program.
2006 - Washington says willing to join multilateral nuclear talks with Iran if it suspends nuclear enrichment.
2009 - US President Barack Obama takes office and tells Iran's leaders he would extend a hand if they would "unclench their fist" and persuade the West they're not trying to build a nuclear bomb.
2009 - Britain, France and the United States announce Iran is building a secret uranium-enrichment site at Fordow. Iran says it disclosed the site to the UN nuclear watchdog earlier in the week.
2009-2012 - Nuclear negotiations between major powers and Iran largely stall.
2012 - US law goes into effect giving Obama power to sanction foreign banks, including the central banks of US allies, if they fail to reduce imports of Iranian oil. The result is a drastic reduction in Iranian oil sales and a sharp downturn in Iranian economy.
2012 - US and Iranian officials begin secret talks, which intensify in 2013, on the nuclear issue.
2013 - Pragmatist Hassan Rouhani is elected Iran's president on platform of improving Iran's relations with the world and its economy. Obama and Rouhani speak by telephone in the highest-level contact between the two countries in three decades. Iran and six major powers - the US, UK, China, France, Germany and Russia - reach an interim pact under which Iran agreed to curb its nuclear work in return for limited sanctions relief.
2015 - Iran and six powers strike an agreement on July 14 in return for significant easing of US, UN and EU sanctions.
2016 - On Sunday (AEDT), US and Iran conduct prisoner swap, four Americans imprisoned in Iran freed in return for clemency for at least seven Iranians convicted or awaiting trial in the US. A fifth American is released separately. International Atomic Energy Agency confirms Iran has taken steps to restrict its nuclear program; US, UN, EU ease sanctions on Iran.