Nuclear implications of the Israel-Iran conflict
SUMMARY
The Joint Comprehensive Plan of Action (JCPoA) negotiated with Iran by President Barak Obama was adopted by the UN Security Council in 2015. It is a crucial part of the context in which the current military exchanges between Israel and Iran should be understood.
Obama’s nuclear deal with Iran is considered to be one of the most important and successful nuclear arms limitation agreements in recent times. However, during his first term of office, President Donald Trump unilaterally withdrew the United States from the agreement.
In his second term, Trump has set his sights not only on removing Iran’s ability to develop nuclear weapons, but also on denying it ballistic missile capability and permanently degrading Iran’s influence in the region. This is the background against which military engagements between Israel and Iran, and between the US and Iran, have taken place.
This briefing explains the terms of the JCPoA and the impact of US withdrawal. It considers the goals of the Trump administration, assesses the dangers posed by illegal military strikes on Iran’s nuclear facilities, and warns against growing calls from Israel and the US for regime change.
Whatever the outcome, the impact of the current military exchanges will have a lasting impact on the future of the region and beyond. The briefing explains why we need an immediate, lasting ceasefire and cessation of hostilities, leading to a nuclear weapons-free Middle East in the longer term.
Background
Concerns among western allies about Iran’s development of a civil nuclear power programme go back over many years. Iranian nuclear development dates back to the 1950s, begun with assistance from the US Atoms for Peace programme. In 1970, Iran ratified the nuclear Non-Proliferation Treaty (NPT), which allows states to pursue civil nuclear power for peaceful purposes.
Over two years, President Obama successfully negotiated an agreement with Iran, the Joint Comprehensive Plan of Action (JCPoA), which lifted nuclear-related sanctions on Iran in return for a commitment to restrict Iran’s nuclear programme to the development of civil nuclear power for peaceful purposes and permit inspections by the UN’s watchdog, the International Atomic Energy Agency (IAEA).
Iran, Germany and the five permanent members of the UN Security Council – China, France, Russia, the UK, and USA – signed up to the JCPoA. It came into effect on 18 October 2015 when UN Security Council members adopted UNSC Resolution 2231.
The JCPoA is widely regarded as one of the most important and successful arms limitation agreements of recent times. In 2018 however, President Donald Trump unilaterally withdrew the United States from the agreement and imposed unilateral sanctions on Iran. Trump claimed sanctions had been lifted in exchange for ‘very weak limits on the regime’s nuclear activity’ and ‘no limits at all on its malign behaviour around the world’.
Under the terms of UNSC 2231 the JCPoA remains in force until 18 October this year. However, US withdrawal has, in effect, blocked any chance of progress that the Iran nuclear agreement offered. At the same time, Israel’s status as an internationally acknowledged though undeclared nuclear weapons state remains unchallenged by the United States and its allies.
The Joint Comprehensive Plan of Action
The JCPoA lifted nuclear-related sanctions on Iran in return for strict limits on Iran’s ability to develop nuclear weapons, and guards against Iran developing a covert nuclear weapons programme by requiring it to:
- restrict uranium enrichment;
- limit the numbers and types of centrifuges in operation, which separate out the different uranium isotopes;
- substantially reduce the size of its enriched uranium stockpiles;
- render inoperable the Arak heavy-water reactor, a type of reactor capable of producing a weapons-grade plutonium by-product; and
- permit wide-ranging inspections by the International Atomic Energy Agency (IAEA), the UN’s nuclear watchdog.
US claims that Iran violated the terms of the NPT have never been proved. When the US withdrew from the agreement in 2018, successive IAEA inspections had confirmed Iran did not possess nuclear weapons. These reports were accepted by all parties to the JCPoA, including the US Department of Defense and other US agencies. Everyone agreed Iran was meeting its obligations.
The US Council on Foreign Relations noted at the time: ‘President Trump’s decision to withdraw from the landmark agreement jeopardises the unprecedented visibility international inspectors now have into Iran’s nuclear programme.’
Trump’s then Secretary of State Mike Pompeo, also a supporter of withdrawing from the JCPoA, claimed the ‘weak provisions’ of the deal ‘merely delayed’ Iran’s nuclear capability. In a speech shortly after US decertification of the JCPoA, Pompeo said the US would only be prepared to end sanctions if Iran agree to:
- permanently and verifiably abandon in perpetuity any military dimension of its nuclear programme;
- stop enrichment and never pursue plutonium reprocessing;
- halt development of nuclear-capable ballistic missile systems; and
- provide the IAEA with unqualified access to all sites throughout the entire country.
UK sanctions against Iran
The UK, along with France and Germany, known as the E3 parties to the JCPoA, did not decertify the JCPoA, and remain parties to UNSC 2231. However, they claimed that Iran’s ‘consistent and severe non-compliance’ with the terms of the JCPoA warranted the retention of sanctions and followed the US in introducing domestic sanctions against Iran.
Under the terms of the JCPoA all previous UN sanctions can be re-imposed in the event of ‘significant non-performance by Iran’, known as the snapback provisions. UN-imposed sanctions are international sanctions. However, the JCPoA does not provide for domestic sanctions to be applied individually by states, nor if there is significant evidence of non-performance.
To date Britain continues to apply domestic sanctions which were introduced into UK law as the Iran (Sanctions) (Nuclear) (EU Exit) Regulations 2019. This statutory instrument allows the government to impose sanctions without having to seek parliamentary approval.
Trump’s second term
On 4 February 2025, Trump signed National Security Presidential Memorandum NSPM 2 which states that:
- Iran should be denied a nuclear weapon and intercontinental ballistic missiles;
- Iran’s terrorist network should be neutralized; and
- Iran’s aggressive development of missiles, as well as other asymmetric and conventional weapons capabilities, should be countered.
Not only does Trump’s policy break with the approach of the Obama administration, it also represents a breach of the bipartisan approach of past presidents – both Republican and Democratic – which focussed on preventing Iran’s acquisition of nuclear weapons, without linking this to ballistic missile capability or Iran’s regional influence.
This shift in approach has already proved to be both wrong-headed and dangerous.
Iran’s approach
Whilst inspections of Iranian nuclear facilities confirmed Iran was honouring the JCPoA, since 2018 there have been growing concerns that US withdrawal and reimposition of sanctions has prompted Iran to disregard some of the constraints imposed on it. Some sources have reported that Iran is closer to acquiring weapons-grade uranium – though estimates vary widely, from five years or more, to unsubstantiated assertions that this could be merely weeks away.
The Iranian leadership continues to seek a nuclear dialogue with the United States. Iran’s leadership called for talks throughout Trump’s election campaign in 2024, during the presidential transition and since his inauguration. It remains, at least for the moment, a signatory to the NPT.
Iran asserts:
- its nuclear programme is for peaceful purposes,
- its willingness to return to its JCPoA obligations, if sanctions are lifted.
- that parties to the JCPoA have violated the terms of the agreement, by failing to meet their commitments on sanctions relief.
Since 2023, Israel’s military aggression has spread from the Occupied Palestinian Territories to Lebanon, Syria, Iraq, and now to Iran. This is despite growing international outrage at Israel’s many breaches of international and humanitarian law, and encouraged in part by the failure of the Biden administration to take effective action to curb Israel’s military campaigns.
In regional terms, Iran is a significant military force. As recent exchanges demonstrate, it retains the ability to strike with force beyond its borders, despite the fact that Israeli attacks have significantly weakened Iran’s military leadership and depleted its armaments. Nevertheless, its military capacity bears little comparison with that of the US or Israel.
This has led Iranian nuclear hawks to increase their calls for the country to acquire nuclear weapons, wrongly arguing this will deter – rather than encourage – attacks by Israel and the United States. As a result of the June 2025 attacks by Israel, the Iranian parliament is considering withdrawing from the NPT.
Israel’s stance
Prime Minister Benjimin Netanyahu regarded the JCPoA as an ‘historic mistake’. Even without nuclear capability, he said, Iran’s actions were inconsistent with Israeli interests and objectives. Yossi Cohen, head of Mossad, Israel’s National Intelligence Agency (2016-2021), expressed this more bluntly: ‘with the nuclear agreement or without it, Iran will continue to serve as the main threat to Israel’s security.’
Unsurprising then, the current aims of Israel’s military strikes include degrading Iran’s nuclear programme, but also go beyond that. Israel has targeted ballistic missile facilities as well as key military figures and nuclear scientists. The scale and choice of these targets, as well as Netanyahu’s own words, are rightly understood as seeking to destabilise the Iranian leadership and bring about regime change.
In a video address shortly after Israel’s first attack on Friday 13 June, Netanyahu, made a direct appeal to the Iranian people. ‘The Islamic regime which has oppressed you for almost 50 years, threatens to destroy the State of Israel,’ he said. ‘As we achieve our objective, we are also clearing the path for you to achieve your freedom.’
Trump has also made clear his intentions for regime change, including oblique references to Iran’s Supreme Leader Ayatollah Ali Khamenei being an ‘easy target’ for assassination.
Damaging, long-term impacts of US-led military actions
Afghanistan (2001 to 2021)
Estimates put the number of deaths over 240,000, of which over 70,000 were civilians. The Doha Agreement of February 2020 between the US and Taliban ended the occupation. The last troops withdrew in 2021, leaving Afghans to their fate at the hands of the Taliban. Afghanistan today is still experiencing a severe and many-sided humanitarian crisis. Extreme repression and human rights violations continue. The Taliban carries out public executions, stonings and floggings. Enforced disappearances, unlawful detentions, arbitrary arrests, torture and other forms of ill-treatment are commonplace. The Taliban has failed to lift restrictions on women and girls as it suggested at the time of Doha. Ethnic groups, including religious minorities, are marginalised and subject to forced evictions.
Iraq (2003 to 2011)
At least 500,000 Iraqi people were killed as a result of the US-led invasion and occupation. The last US troops withdrew in December 2011, marking the official end of the war. As the state structures of Iraq were destroyed and dismantled, the Islamic State of Iraq and Syria (ISIS) moved in to fill the gap. The destruction of the Iraqi state led to a series of conflicts between armed groups contesting for power. In January 2018, for example, ISIS suicide bombers killed 27 people in the centre of the capital Baghdad. US attacks continued throughout Trump’s first term. A US airstrike on Mosul in March 2017, for example, known as the Mosul Massacre, killed between 2-300 civilians. It was the largest civilian death toll of any airstrike during the invasion. The IS insurgency was a direct result of the war in Iraq. It continues to this day.
June 2025 military exchanges and ceasefire
Following Israel’s bombing of Iranian nuclear facilities on Friday 13 June, Israel and Iran exchanged fire over many days. Hundreds of civilians were killed and injured and domestic infrastructure destroyed on both sides. In response, Iran’s parliament is considering a bill to withdraw from the NPT.
Strikes on nuclear facilities have the potential to kill thousands of civilians and unleash levels of radioactivity into the environment capable of destroying human life and inflicting environmental damage on a regional scale and beyond.
IAEA Director General Rafael Grossi called on all parties to exercise maximum restraint and avoid further escalation, reiterating that: ‘nuclear facilities must never be attacked, regardless of the context or circumstances, as it could harm both people and the environment. Such attacks have serious implications for nuclear safety, security and safeguards, as well as regional and international peace and security.’
Grossi confirmed an Israeli military strike on Natanz had hit the underground enrichment plant, damaging its power supply, that several facilities had been destroyed at the Isfahan nuclear complex, but there was no apparent damage to the Fordow enrichment plant.
Israel’s objective of destroying Iran’s nuclear capability was in breach of the Geneva Convention which defines the rules of conduct for all states during armed conflict. Protocols I and II specifically prohibit attacks on nuclear facilities.
Israel alone, however, does not have the military means of degrading Iranian nuclear facilities buried deep underground. It openly called on the United States to use its more destructive weaponry to penetrate these underground facilities.
On Sunday 22 June, the US launched a bombing campaign on Iran’s Fordow, Natanz and Esfahan nuclear facilities, using its B-2 stealth bombers to launch 30,000lb ‘bunker buster’ bombs. The IAEA has reported substantial damage to all facilities.
Following the US bombing campaign, Iran retaliated by bombing the US base, Al-Udeid, in Qatar. Subsequently, President Trump announced that a ceasefire between Israel and Iran had been agreed.
Securing a permanent ceasefire and an end to the hostilities is the only way to remove the risk to human life and the environment that attacks on nuclear facilities pose. It is also critical with regard to avoiding a wider war that could draw in other nuclear states. The actions of US and Israel must not be allowed to determine UK policy. The British government cannot stand on the sidelines. Prime Minister Keir Starmer must do all in his power to maintain a ceasefire and the cessation of hostilities.
Nuclear weapons-free Middle East
Whilst the maintenance of the ceasefire is critical to the resumption of talks in the short term, charting a path to a peaceful future for the Middle East is also essential. CND believes the establishment of a nuclear weapons-free zone across the region is an indispensable foundation for peace.
Since the 1960s, five nuclear weapons-free zones have been established by agreements which ban the use, development, and deployment of nuclear weapons on the territories of participating countries. They are recognised by the United Nations, and cover 115 countries – from the Association of Southeast Asian Nations (ASEAN) countries, Central Asia, and Africa, to the South Pacific, and Latin America and the Caribbean.
Israel’s actions in seeking the destruction of Iran’s nuclear programme – whilst refusing to acknowledge its own nuclear arsenal, not allowing IAEA inspections nor signing up to the nuclear Non-Proliferation Treaty – are the height of nuclear hypocrisy. As currently the only other country in the region with the potential to become a nuclear weapons state in the foreseeable future, Iran’s cooperation in any solution is equally essential. However, such a treaty is also critical to halt the potential of further nuclear proliferation from countries including Saudi Arabia.
The need for a nuclear weapons-free zone in the Middle East is more urgent than ever. Britain, as a primary sponsor of the UN resolution calling for this Treaty has a critical role to play in progressing this.
Global nuclear disarmament
This crisis also exposed the wider nuclear hypocrisy of all nuclear weapons states, including those that have signed up to the NPT. Instead of abiding by their commitments in the NPT to take steps to disarm their nuclear weapons, these states are increasing and modernising their arsenals.
Furthermore, countries like Britain, justify the use of their nuclear weapons against non-nuclear weapons states that are signatories to the NPT who are in ‘material breach of those non-proliferation obligations’.
Far from countering proliferation, these actions of nuclear weapons states only increase the risk of non-nuclear weapons states seeking their own nuclear arsenals.
It is therefore vital that public pressure is strengthened nationally and globally for nuclear disarmament, including the adherence to international disarmament frameworks like the NPT and the Treaty for the Prohibition of Nuclear Weapons.
25 June 2025