The US attack on Iran marks a watershed moment for the Middle East after years of tension over the Iranian nuclear programme.
For two decades, Iran has been accused by Israel, the US and others of running a secret weapons programme and enriching uranium to develop an atomic bomb.
Iran insists its nuclear programme is peaceful. In 2015 it agreed to curb its activities in exchange for sanctions relief, but that deal later unravelled and tension soared again.
A push for a new deal began after US President Donald Trump returned to power in January. But he always warned military strikes were an alternative option. Just over a week after Israel attacked Iran, the US entered the war.
2013-2019: Deal made, then broken
November 2013: Iran and several global powers announce an interim deal that temporarily curbs Tehran's nuclear programme and unfreezes some Iranian assets, setting the stage for fuller negotiations.
April 2015: A framework nuclear deal is announced, outlining long-term restrictions on Iran’s nuclear programme and the removal of many international sanctions.
July 2015: A full nuclear deal is announced between Iran and major powers including the US, Britain, Russia and China. It is known as the Joint Comprehensive Plan of Action.
May 2018: Donald Trump, during his first term as president, unilaterally withdraws the US from the nuclear agreement, calling it the “worst deal ever”. Israeli Prime Minister Benjamin Netanyahu had lobbied for a withdrawal.
August 2018: The Trump administration begins to restoresanctions on Iran that were lifted under the JCPOA, targeting a range of sectors from carpets and pistachios to gold and commercial aircraft.
November 2018: The US re-enforces the most onerous sanctions that were lifted under the deal, targeting Iran’s banking and oil sectors.
April 2019: Mr Trump designates Iran’s Islamic Revolutionary Guard Corps as a foreign terrorist organisation, marking the first time the US has blacklisted part of another nation’s military in this way.
May 2019: Iran announces it will begin breaching the accord, setting a 60-day ultimatum for Europe to compensate for American-led sanctions before it begins enriching uranium to higher levels.
July 2019: Iran announces it has exceeded the nuclear deal’s curbs on its low-enriched uranium stockpile.
September 2019: Iran begins spinning advanced centrifuges prohibited under the 2015 deal.
November 2019: Iran injects uranium gas into centrifuges at its underground Fordow plant.
2020: Suspected sabotage and a new US president
January 3, 2020: A US drone strike in Baghdad kills Qassem Soleimani, the head of the IRGC's foreign operations branch, after a series of tit-for-tat attacks between Iran and the US.
January 8, 2020: In retaliation for Soleimani's killing, Iran launches a barrage of missiles at US bases in Iraq. More than 100 US service members suffer brain injuries.
July 2020: An explosion tears apart a centrifuge production plant at Iran’s Natanz nuclear enrichment facility. Iran blames the blast on Israeli sabotage.
October 2020: A decade-long UN arms embargo on Iran that banned it from purchasing foreign weapons expires as scheduled under the nuclear deal, despite American objections.
November 2020: Joe Biden wins the US presidential election.
2021: IAEA oversight weakened
January 2021: Iran begins enriching uranium up to 20 per cent and seizes a South Korean-flagged oil tanker near the Strait of Hormuz.
February 2021: Inspectors at the International Atomic Energy Agency lose access to surveillance cameras, as well as data from enrichment monitors and electronic seals, amid a stand-off with Iran. Tehran pledges to hold on to the tapes and give them back when granted sanctions relief.
April 6, 2021: Iran and the new Biden administration begin indirect negotiations in Vienna over how to restore the nuclear deal.
April 11, 2021: A second attack targets the Natanz nuclear site, with suspicion falling on Israel.
April 16, 2021: Iran begins enriching uranium up to 60 per cent – its highest purity so far and only a short technical step from weapons-grade levels of 90 per cent.
June 19, 2021: Ebrahim Raisi, a hardline ally of Iranian supreme leader Ayatollah Ali Khamenei, is elected Iran's president.
December 2021: The IAEA says Iran has begun feeding a cascade of 166 advanced IR-6 centrifuges at its underground Fordow facility. A deal is reached to reinstall cameras at another site.
2022-23: Opportunities lost
March 2022: Nuclear talks in Vienna break off without an agreement, after Russia invades Ukraine and makes new demands on sanctions and trade with Iran.
June 2022: The IAEA board of governors censures Iran for failing to provide answers on man-made traces of uranium found at three undeclared sites. Iran begins disconnecting dozens of IAEA surveillance cameras.
August 2022: Negotiators from Iran, the US and the EU hold indirect talks on a tentative deal, but it falls apart. France, Germany and Britain say Iran “has chosen not to seize this critical diplomatic opportunity”.
February 2023: Iran acknowledges an accusation from inspectors that it enriched particles of uranium to 84 per cent purity for the first time. The issue ultimately is settled, but puts new pressure on negotiators.
October 7, 2023: Hamas militants from Gaza storm into Israel, killing 1,200 people and taking 250 others hostage. It begins the worst ever war between Israel and Hamas. Iran, which has armed Hamas, offers support to the militants. Regional tensions spike.
2024-2025: Return of Trump
June 2024: The IAEA board of governors censures Iran for failing to co-operate with the agency. The agency says Iran has started up new cascades of advanced centrifuges and plans to install others.
November 2024: Mr Trump wins the US presidential election. During the campaign he said repeatedly that Iran "can't have a nuclear weapon".
April 2025: Mr Trump makes a surprise announcement that the US and Iran will begin talks on Tehran's nuclear programme. Three rounds of talks follow in Muscat and Rome, with positive progress reported. Iran suggests it would welcome US investment.
May 11, 2025: A fourth round of talks take place in Muscat, described by Iranian Foreign Minister Abbas Araghchi as “difficult but useful”.
May 13, 2015: In a speech in Riyadh, Mr Trump condemns Iran's actions but offers its leaders a "new path" to peace, saying the "choice is theirs" on whether to make a del.
May 23, 2025: A fifth round of talks takes place in Rome with signs of limited progress emerging.
May 31, 2025: The US says it sent Iran a proposal for a nuclear deal via the Omani Foreign Minister, which Mr Khamenei says is “against” Iranian interests.
June 8, 2025: Iran announces it will present a counter-proposal after calling for guarantees that US sanctions will be lifted under a new deal.
June 11, 2025: Mr Trump says he is “less confident” of reaching a deal. Later, the US announces it is preparing to evacuate non-essential staff from the US embassy in Baghdad.
June 12, 2025: The IAEA finds Iran in breach of non-proliferation duties.
2025: War breaks out
June 13, 2025: Israel mounts a surprise attack on Iran. Several of Iran's top military commanders are killed in an aerial bombardment known as Operation Rising Lion. A full-scale air war ensues as Iran hits back with hypersonic missile and drone strikes.
June 16, 2025: Israel bombs an Iranian TV station on the fourth day of its campaign as the air war spreads into civilian areas. Iran destroys buildings in Tel Aviv.
June 17, 2025: Mr Trump demands Iran's "unconditional surrender" as his early departure from a G7 summit fuels speculation the US is set to enter the war.
June 22, 2025: The US enters the war, attacking Iranian nuclear sites such as Fordow with its "bunker-buster" bombs. Iran vows to respond.
