European leaders’ responses to the recent Israeli and United States attacks against Iranian nuclear facilities have been striking for both their muted tone and their apparent acceptance of violations of international law. They also stand in stark contrast to the aftermath of attacks on civilian nuclear energy infrastructure in Ukraine during 2022, when the European Union quickly condemned Russia for violations of international law.
French President Emmanuel Macron acknowledged that the US strikes on three Iranian nuclear facilities—at Fordow, Isfahan and Natanz—on 22 June lacked a legal framework, but nevertheless said there was ‘a legitimacy in neutralizing Iran’s nuclear structures’. A joint statement by France, Germany and the United Kingdom similarly justified the US attacks by stressing the need to prevent Iran from acquiring a nuclear weapon, while also affirming ‘support for the security of Israel’. EU officials expressed ‘deep concern’ about the situation but referred to Israel’s ‘right to defend itself’, pointing to Iran as the main source of regional instability.
Noting that the attacks on Iran undermined the 1968 Treaty on the Non-Proliferation of Nuclear Weapons (NPT), experts have called for Europeans to stand up in defence of multilateral legal and normative frameworks. While these calls have thus far not been heeded, it is important for European leaders to change approach and facilitate a diplomatic exit from the situation—which remains unsustainable despite the fragile ceasefire reached by Iran and Israel on 25 June.
No legal basis for the attacks
It is true that there were concerns about Iran’s nuclear weapons ambitions related to its accumulation of enriched uranium since 2019, although none of it was enriched to weapons grade. On 12 June 2025 the Board of Governors of the International Atomic Energy Agency (IAEA) adopted a resolution that found Iran to be in non-compliance with its safeguards agreement with the agency. The USA claimed the most recent report of the IAEA Director General ‘shows clearly that Iran has been continuing to accelerate its nuclear activities without any credible civilian justification’. Yet the IAEA Board resolution was largely based on outstanding issues related to clarifying Iran’s past nuclear activities, dating back to more than 20 years ago. As recently as March 2025, US intelligence assessments indicated that Iran had not sought to resume weapons activities since suspending its nuclear weapons programme in 2003. Furthermore, the IAEA resolution was hardly unanimous, passing with 19 votes for, 3 against, and 11 abstentions.
Expert opinions vary as to how much time it would have taken for Iran to build a nuclear weapon had it decided to pursue that route. However, Iran’s nuclear programme—whose civilian nature has long been verified by regular IAEA inspections—posed no immediate threat to either Israel or the USA. At best, justification for the attacks on Iran rests on the logic that its nuclear programme might pose a future threat, which instead suggests preventive self-defence—an argument similar to the reasoning presented by the George W. Bush administration in the US invasion of Iraq.
In other words, the attacks against Iran’s civilian nuclear sites amount to aggression that violates international law, as do the Israeli assassinations of Iranian nuclear scientists, some in their residences. International humanitarian law prohibits attacks directed against civilians and civilian objects.
The attacks on Iran come on top of Israel’s multiple violations of international humanitarian law committed against the Palestinians in Gaza and continuing attacks on civilians. Some of those acts also constitute genocide according to United Nations experts and various organizations, and as submitted in South Africa’s ongoing case against Israel at the International Court of Justice, which is supported by several other states. European countries have provided arms and political support to Israel in Gaza—and now seem to be relinquishing defence of international law once again in the war in Iran.
Another blow to the Non-Proliferation Treaty
Contrary to the view of the French president and other leaders, the attacks on Iran cannot be seen as legitimate. They were initiated against a non-nuclear weapon state—which as an NPT party has an ‘inalienable right’ to pursue nuclear energy—by Israel, a nuclear-armed state whose own nuclear activities have escaped international scrutiny due to its refusal to join the treaty. The presence of nuclear-armed states outside the NPT has long undermined its credibility, which in recent years has also been damaged by the frustration of non-nuclear weapon states over the lack of disarmament progress among nuclear-armed states. The decision by the USA—an NPT depository state—to join Israel in the war on Iran exacerbates structural problems in a way that calls into question the NPT’s sustainability.
In response to the Israeli and US attacks, on 25 June the Iranian parliament passed a bill calling for the country to suspend all cooperation with the IAEA. If it is endorsed by the Iranian government, this bill would halt the implementation of the NPT-based safeguards agreement between the agency and Iran—which until now has provided a high degree of transparency on its nuclear activities, enabling precise IAEA estimates of Iranian enriched uranium stockpiles. Following the first wave of Israeli strikes on Iranian nuclear facilities—which additionally risked radiological disaster—Iran broke the IAEA seals and relocated the containers used to store enriched uranium. As a result, and as acknowledged by both the USA and the IAEA, the location of the country’s fissile material stockpiles is currently unknown. Rather than helping to prevent the spread of nuclear weapons, the attacks have thus eroded the most important verification mechanism for ensuring non-proliferation.
While European leaders are calling for Iran to engage in negotiations, it is unclear what a diplomatic exit from the current situation would look like. US President Donald J. Trump has insisted that Iran should not be allowed to enrich any uranium, a demand that Iran has long rejected and which it is unlikely to accept despite the damage to its enrichment facilities caused by the war. At the same time, potential compromise solutions such as those discussed in the Iranian–US talks prior to the war seem unfeasible because any nuclear deal involving Iran and the USA would likely need to be verified through IAEA inspections—which would be blocked if the parliamentary bill suspending cooperation with the IAEA is endorsed.
New uncertainties
Despite the current ceasefire, the war on Iran might not yet be over and there is considerable scope for further escalation. In his most recent statement on the matter, IAEA Director General Rafael Grossi estimated that Iran could resume uranium enrichment in a ‘matter of months’. US intelligence also suggests the military operation against Iran’s nuclear sites was significantly less effective than initially claimed, setting back any hypothetical nuclear weapons programme by mere months. Even beyond physical capabilities, Iran retains extensive expertise that will allow it to eventually reconstitute facilities that have been damaged or destroyed. This new uncertainty about Iran’s nuclear activities created by the war thus raises the risk of open-ended aggression, as experts have long warned.
Israeli and US statements also suggest potential mission creep towards regime change, again reminiscent of the 2003 war on Iraq, which was initially justified in terms of counterproliferation (related to weapons of mass destruction that Iraq did not in fact possess). Notably, North Korea withdrew from the NPT in 2003, believing that without a nuclear deterrent it might face the same fate as Iraq.
The possibility of Iran’s withdrawal from the NPT thus looms, as the use of force against its territorial integrity can constitute a circumstance in which ‘extraordinary events have jeopardized [its] supreme interests’, providing cause for withdrawal according to the treaty’s Article X. Such a withdrawal would have significant implications, and in the long term may act as a catalyst for further nuclear proliferation in the region and beyond.
The urgent need for a diplomatic solution
Even if the war has destroyed prospects for Iranian–US diplomacy, there might still be a diplomatic way out. Notably, Iran and other Gulf states could re-explore possibilities for a regional non-proliferation arrangement—which they were already doing as part of the Iranian–US talks in the run-up to the Israeli attacks. Instead of the idea of a multilateral fuel cycle discussed in that context, a regional arrangement could also take on simpler forms involving mutual nuclear transparency and restraint.
As an alternative to IAEA safeguards, such an arrangement could be verified through a regional mechanism modelled on the Brazilian–Argentine Agency for Accounting and Control of Nuclear Materials (ABACC). By establishing a means to build confidence in the peaceful nature of the nuclear activities of Iran and other regional states, such an arrangement could provide a powerful argument against further acts of aggressive counterproliferation.
However, this or any other diplomatic solutions that might still be possible would need strong backing from the international community—including European states. These states played a crucial role in the negotiations leading up to the Joint Comprehensive Plan of Action (JCPOA)—the 2015 compromise agreement with Iran that appeared to solve what had previously seemed an intractable crisis. And, following the decision in 2018 by the first Trump administration to withdraw from the JCPOA, European leaders admirably expended considerable effort on trying to revive the agreement in the interests of non-proliferation.
Now, too, European policymakers should do their utmost to promote diplomatic solutions following these attacks on Iran, to prevent further damage to the NPT and the breakdown of regional and international stability. However, in order to do this with credibility, they need to revise their position by insisting that the USA and Israel adhere to international law—and take all steps to ensure that aggression by nuclear-armed states against a non-nuclear weapon state is not seen as permissible.