On 13 June 2025, Israel began a series of airstrikes and missile strikes on Iran. Over the last week events have spiralled, with both countries exchanging missile and drone attacks, causing civilian casualties, and on 22 June, the US joined the war, striking three key nuclear facilities in Iran: Fordow, Natanz, and Isfahan.
There is a narrative around the nature of Iran’s nuclear programme, fuelled by misinformation and disinformation, speculating whether Iran is building (or already possessing) a nuclear weapon. To do that, it is important to understand the background and context to the dispute.
Below is a timeline outlining a history of Iran’s nuclear programme and its approach to nuclear diplomacy, both with the US specifically, and the wider international community throughout the last decades.
Timeline
1957: Iran began developing a nuclear programme, with backing and support from the US under the ‘Atoms for Peace’ programme.
1964: Iran signs and ratifies the Partial Nuclear Test Ban Treaty, which prohibits nuclear weapon tests in the atmosphere, in outer space and under water.
1968-70: Iran signs and later ratifies (becoming a member state of) the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) as a non-nuclear weapon state. This international legal treaty is a commitment by non-nuclear states that they will not proliferate nuclear weapons. In exchange, the five legally-recognised nuclear weapon states (China, France, Russia, United Kingdom, and the United States), are obligated to pursue negotiations to disarm. This is often referred to as the NPT’s ‘grand bargain’.
1974: Iran establishes the Atomic Energy Organisation of Iran.
In the same year, Iran and Egypt co-sponsor a resolution at the UN for a Nuclear Weapon Free Zone in the Middle East. This later became a proposal for a Nuclear Weapon Free Zone and a Zone free of all Weapons of Mass Destruction.
In this year, Iran’s then-ruler, Shah Mohammad Reza Pahlavi, loans 1 billion dollars to France to help build the Eurodif nuclear consortium. Eurodif was a multinational uranium enrichment facility based in France, developed by several European partners, and also Iran. Iran’s loan entitled it to 10% of the enriched uranium produced by the facility. Future disagreements between Iran and France regarding this agreement, including payment of the loan, pursued.
1979: The Islamic Revolution ushers in a new government in Iran, now the Islamic Republic of Iran. The US withdraws its support for Iran’s nuclear programme.
Iran cancels its Eurodif agreement and stops paying for deliveries of enriched uranium, and demands France repay the one billion dollar loan (plus interest), leading to a legal dispute. Iran never received any nuclear fuel from the Eurodif facility.
1995: At the 1995 NPT Review and Extension Conference, States Parties adopt an indefinite extension of the treaty, along with a resolution towards a Weapons of Mass Destruction Free Zone in the Middle East (WMDFZME), following on from Egypt and Iran’s proposal in the 1970s.
However, in the years following, Iran is discovered to have built undeclared enrichment sites at Natanz and Arak.
2003: In May 2003, Iran makes a proposal to the US which includes a request for negotiations to lift US sanctions on Iran, and offers full transparency around Iran’s nuclear programme, including accession to the Additional Protocol. The US dismisses this proposal.
In June 2003, the IAEA reports that Iran has failed to meet its obligations under its Comprehensive Safeguards Agreement with the IAEA.
In October 2003, under the Tehran Declaration, Iran agrees to suspend uranium enrichment, and Ayatollah Khamenei, Iran’s Supreme Leader, suspends Iran’s nuclear weapons programme specifically. A fatwa is issued that forbids the production or use of any weapon of mass destruction (including nuclear weapons).
Iran continues to maintain a nuclear programme for peaceful purposes, including for nuclear energy, medical purposes, and food and agriculture.
2005: Under the leadership of the new President, Mahmoud Ahmedinejad, Iran resumes uranium enrichment, citing its right to a nuclear power programme as a member state of the NPT.
Ahmedinejad does not welcome attempts at diplomatic negotiations to address concerns around its nuclear programme, but proposals and attempts at negotiations are exchanged between Iran and European states through the EU3/Iran Political and Security Working Group.
2006: In February 2006, the IAEA Board of Governors reports Iran to the UN Security Council (UNSC).
Iran refuses to stop its uranium enrichment programme, maintaining it is not developing nuclear weapons. Some states, such as the US and its European partners, however, continue to have growing concerns around Iran’s reasons for enrichment, fearing a nuclear threat.
Four UNSC resolutions are passed, including permitting states to impose national sanctions on Iran, with theUS proceeding to place further heavy sanctions on Iran. Since then, UN resolutions have extended the nature of these sanctions.
2009: An undeclared underground enrichment site near Qom in Iran is discovered.
Following the election of US President Barack Obama, the P5+1 (China, France, Russia, UK, US and Germany) begin to resume attempts at negotiations with Iran around its nuclear file.
2010: Iran reaches an agreement with Brazil and Turkey agreeing to a nuclear fuel swap, called the Tehran Declaration (different from the Tehran Declaration of 2003). The agreement also recalls “the right of all State Parties, including the Islamic Republic of Iran, to develop research, production and use of nuclear energy (as well as nuclear fuel cycle including enrichment activities).” The US, France, and Russia reject this agreement.
2015: After significant diplomatic efforts, Iran reaches a deal with the US and the rest of the P5+1 (with the European Union also participating in the process), called the ‘Joint Comprehensive Plan of Action’ — the JCPOA. The JCPOA was a landmark deal, signalling easing security tensions/concerns in the Middle East region and internationally, and a positive turn in US-Iran relations.
Under the agreement, Iran agreed to dismantle large portions of its nuclear programme, and allowed its facilities to be under extensive inspections and international oversight, specifically with the International Atomic Energy Agency (IAEA). The IAEA is the watchdog for national nuclear programmes.This was in exchange for sanctions relief worth billions of dollars. Iran also agreed to implement the Additional Protocol to their IAEA Comprehensive Safeguards Agreement, which allows inspectors to access any site anywhere in the country they deem suspicious.
Of the IAEA’s entire budget, the highest portion is dedicated to monitoring, verification, and oversight of Iran’s nuclear programme — more than any other state.
2018: Following his election, President Donald Trump unilaterally withdraws the US from the JCPOA, leading to the breakdown of the agreement. Trump goes on to reimpose crippling economic sanctions on Iran, which had honoured its commitments to the JCPOA in good faith since 2015.
2020: The Trump administration orders a drone strike killing Iran’s top military commander, General Qassem Soleimani, along with several others. Iran resumes nuclear activities with less oversight and monitoring by the IAEA (due to Iran denying them access), and increases its enrichment activities.
The international community continues to share its concerns around Iran’s nuclear enrichment programme, but Iran maintains that it is committed to its religious fatwa and is not intending to develop nuclear weapons.
2025: In March 2025, US intelligence formally assesses and acknowledges that Iran is not building a nuclear weapon and has not resumed the weapons programme it suspended in 2003.
At the third Preparatory Committee of the NPT in April-May 2025, Iran reiterates its support for efforts towards a world free of nuclear weapons through statements delivered during the conference.
Later in the year, the US and Iran return to the negotiating table to try to reach a new nuclear deal. Top Iranian official Ali Shamkhani goes on the record to say Iran is willing to enhance international security, saying “we want a better relationship with the US, we will commit to never having nukes.”
The IAEA publishes its report on Iran’s nuclear programme, highlighting its limited ability for monitoring, verification, and oversight. The IAEA Board of Governors votes that Iran is in non-compliance with its safeguards agreement.
Two months into negotiations, Israel launches strikes across Iran, targeting nuclear facilities and civilian areas. At the time of writing, these strikes are reported to have killed at least 639 people, with reports speculating that Ali Shamkhani was also killed. The US has gone back and forth on whether it is directly ‘involved’ in the strikes. Negotiations come to a standstill, and Iran responds to the strikes with strikes of its own, on Israel.
President Trump posts a series of threats on social media demanding ‘unconditional surrender’ claiming to have ‘complete and total control of the skies over Iran’.
IAEA Director General, Rafael Grossi, reasserts that there is no evidence of Iran developing nuclear weapons, countering narratives claiming Iran’s nuclear threat as justification for war in Iran.
On the 22nd June, President Trump tweeted to announce that the US had formally joined the war with Iran, reportedly striking three nuclear facilities in Iran: Fordow, Natanz, and Isfahan.
In response, Iran targeted US bases in Qatar, namely the Al-Udeid airbase, resulting in no injuries.
In the early hours of the 24th June, President Trump announced a ceasefire agreement between Israel and Iran, brokered by the US and Qatar.
This timeline will be updated to include possible future developments.
Photo: Unsplash