On 12 June 2025, Israel launched a large-scale military campaign, “Operation Rising Lion”, targeting Iran’s military and nuclear sites. Israel justified its operation by claiming that Iran was on the verge of producing nuclear weapons and needed to be stopped urgently. The strikes killed multiple senior Iranian military officials, including Chief of Staff of Armed Forces General Muhammad Bagheri, the head of the Islamic Revolutionary Guard Corps (IRGC) Major General Hossein Salami, and Deputy Commander-in-Chief of the Armed Forces Gholamali Rashid.
Iran retaliated by launching its own military operation, codenamed “True Promise 3,” targeting military installations, air bases, and cities in Israel. As the exchange of fire intensified between the two countries, the conflict escalated into a full-scale war.
Later, on 22 June, the United States entered the war by striking three nuclear sites in Iran. B-2 bombers dropped bunker-buster bombs, and submarines fired Tomahawk cruise missiles to destroy uranium enrichment facilities at Fordow, Natanz, and Isfahan.
As this new war unfolds in West Asia, with Iran’s nuclear sites under attack, the issue of its nuclear programme has once again come to the forefront. This explainer seeks to address some of the most important questions surrounding this crisis.
What is Iran’s nuclear programme?
The Iranian nuclear programme began in the 1950s with support from the United States’ “Atoms for Peace” initiative, which provided essential technology and expertise to developing countries seeking to launch a civilian nuclear programme. It was President Eisenhower’s initiative to ensure these countries’ commitment to peaceful nuclear development by granting them access to necessary expertise and equipment.
Iran joined “Atoms for Peace” in 1957, under the rule of Mohammed Reza Shah, after signing a civilian nuclear cooperation agreement with the U.S. This led to the opening of the Tehran Nuclear Research Centre in 1959, with fuel for its research reactor supplied by the American company, United Nuclear Corporation.
In 1968, when the United Nations Treaty on the Non-Proliferation of Nuclear Weapons (NPT) opened for signature, Iran became one of the earliest signatories. It ratified the treaty in 1970, reaffirming its commitment to a peaceful, civilian nuclear programme. However, the Islamic Revolution of 1979 and the fall of the Shah’s regime dramatically changed Iran’s relationship with the West.
The Iran-Iraq war of the 1980s destroyed much of Iran’s nuclear infrastructure and forced the country to reassess its nuclear programme. In the 1990s, recovering from its war with Iraq, Iran relaunched its civilian nuclear efforts by signing agreements with Russia and China. Simultaneously, it initiated a secret project, reportedly called the Amad Plan, aiming to develop at least five nuclear weapons by 2004. According to several reports, Iran received crucial assistance in uranium enrichment from Pakistani nuclear scientist A. Q. Khan through his smuggling network.
In 2002, the National Council of Resistance of Iran, an exiled Iranian opposition group based in Paris, revealed the existence of secret underground nuclear facilities at Natanz and Arak. The Iranian government dismissed the claims, stating that the facilities were part of its civilian nuclear programme. It entered talks with EU-3 (France, Germany and the UK) and agreed to cooperate with the International Atomic Energy Agency (IAEA). In 2003, following the Tehran Agreement, Iran signed the Additional Protocol to its NPT safeguards agreement, granting the IAEA greater verification powers. However, after Mahmoud Ahmadinejad was elected president in 2005, Iran resumed its enrichment efforts.
How did Western powers react to Iran’s nuclear ambitions?
In 2006, the UN Security Council (UNSC) imposed its first round of sanctions on Iran, blocking the import and export of sensitive nuclear materials and freezing the assets of individuals or entities linked to proliferation-sensitive activities. Iran rejected the sanctions and continued its uranium enrichment operations. In 2009, President Barack Obama revealed that Iran had built another secret nuclear facility at Fordow.
In the following years, Iran was subjected to multiple rounds of UN sanctions over its nuclear programme. In 2010, President Ahmadinejad challenged the Western efforts to curtail Iran’s nuclear activities and declared that the country had produced its first batch of uranium enriched to a higher level.
In June 2013, Hassan Rouhani was elected president of Iran. Two months later, in September, President Obama and Rouhani held a historical phone call, the first contact between the top leaders of both nations since 1979. Subsequently, in November 2013, Iran signed an interim agreement known as the Joint Plan of Action (JPOA) with the IAEA and P5+1 (five permanent UNSC members—the U.S., UK, France, Russia, and China—plus Germany), agreeing to halt uranium enrichment above 5%, reduce its enriched uranium stockpile, and allow broader IAEA inspections. In exchange, Iran received limited sanctions relief, including eased restrictions on trade in gold, petrochemicals, cars, and aircraft parts.
Building on that progress, on 14 July 2015, Iran signed the Joint Comprehensive Plan of Action (JCPOA) with the P5+1 and the European Union (EU), in what was widely regarded as a major foreign policy achievement of President Obama. The JCPOA imposed strict limits on Iran’s nuclear activities, including capping enrichment at 3.67%, reducing the number of centrifuges, and redesigning certain facilities to prevent plutonium production. In return, all nuclear-related sanctions imposed by the UNSC, EU, and the U.S. were lifted, allowing Iran access to billions of dollars in previously frozen assets.
In May 2018, President Trump unilaterally withdrew the U.S. from the JCPOA, calling it “the worst deal ever.” Subsequently, the U.S. launched a “maximum pressure” campaign against Iran, reimposing harsh economic sanctions that targeted its oil exports, banking system, and key industries.
In response, Iran started to breach JCPOA limitations and expanded uranium enrichment to higher purity levels, increased stockpiles of enriched uranium, and restricted IAEA access to its nuclear facilities. In 2020, following the US assassination of General Qassem Soleimani, Iran further distanced itself from the deal, announcing it would no longer place any limitations on its uranium enrichment.
What is Iran’s relationship with the Non-Proliferation Regime?
Although Iran was one of the earliest signatories of the NPT and has long maintained that its nuclear programme is for peaceful purposes, its relationship with global non-proliferation regimes has been marked by mistrust, limited transparency, and frequent disputes. As an NPT signatory, Iran committed not to pursue nuclear weapons and agreed to allow IAEA oversight of its nuclear activities. However, the secret development of its Natanz and Arak facilities, without informing the IAEA, raised serious questions about its intentions and compliance.
Iran’s decision to sign the Additional Protocol to its safeguards agreement in 2003, granting the IAEA greater access to its facilities, was widely seen as a positive step. However, since Ahmadinejad was elected president in 2005, Iran has reduced its cooperation with the IAEA and opened the Fordow enrichment facility.
The 2015 JCPOA again sought to ensure Iran’s commitment to global non-proliferation norms. Under the agreement, Iran accepted rigorous inspections and limits on enrichment. But after the U.S. withdrawal from the deal in 2018, Iran continued violating its commitment to non-proliferation norms and began to increase uranium enrichment levels, expand its stockpile, and curtail IAEA access to its nuclear facilities.
Iran is not a signatory to the Treaty on the Prohibition of Nuclear Weapons (TPNW), adopted in 2017 as the first legally binding international agreement to ban the development, possession, and use of nuclear weapons.
In summary, though Iran remains within the framework of the NPT, its actions, marked by mistrust and a lack of transparency, continue to fuel global concerns about its true nuclear ambitions.
How does it challenge regional stability?
Riven by sectarian tensions, territorial disputes, and historical animosity, the West Asia and North Africa region remains one of the most unstable in the world. Countries such as Saudi Arabia, UAE, Egypt and Israel are highly concerned about Iran’s growing influence in the region, even without the nuclear question. When the prospect of nuclear deterrence is added, these threat perceptions take on a new dimension. If Iran succeeds in developing nuclear weapons, it may encourage countries like Saudi Arabia to pursue similar capabilities, potentially destabilising the regional balance of power.
In recent years, Iran challenged regional rivals through proxy groups such as Hezbollah in Lebanon, Houthis in Yemen, and various militias in Iraq and Syria. It is also the most significant supporter of Hamas, which Israel has designated a terrorist organisation. The possibility that Iran could extend a nuclear umbrella over its proxies raises the risk of emboldened regional aggression.
Although Iran has consistently stated that it has no intention of developing nuclear weapons, the mistrust created by its belligerent activities fuels ambiguity about its true intentions, forcing regional rivals to oppose its nuclear programme. In short, the prospect of a nuclear-capable Iran intensifies rivalries and raises the risk of escalations, threatening peace and stability in the West Asia and North Africa region.
Why is Israel attacking Iran over this issue?
Unlike the Western powers that sought to manage Iran’s nuclear ambitions through diplomacy, monitoring, and sanctions, Israel has historically favoured preemptive military action to neutralise threats before they materialise. This approach is rooted in its military doctrine, shaped by historical precedents such as the 1981 attack on Iraq’s Osirak reactor and the 2007 strike on a suspected Syrian nuclear facility, to prevent hostile regimes from acquiring nuclear weapons.
However, Iran presents a far greater threat than Iraq or Syria ever did. It supports anti-Israeli militant groups like Hezbollah and Hamas, regularly calls for the destruction of the Israeli state, and possesses advanced missiles capable of striking anywhere within Israel. Consequently, Israel doubts Iran’s intentions and believes it is preparing to develop nuclear weapons under the cover of a civil nuclear programme.
According to Israeli assessments, Iran’s nuclear programme has advanced to the point of posing an existential threat, with enough enriched uranium to make nine nuclear weapons. Given Iran’s existing missile capabilities, Israel considers that it cannot afford to delay its response. Therefore, through the strikes, it aims to significantly damage Iran’s nuclear infrastructure and prevent it from developing nuclear weapons.
Although this preemptive strike risks escalation, Israel believes that its action will compel the international community, especially the U.S., to take a firmer stand against Iran.
