The E3 and Tehran have no better option than re-engaging. Failing to do so risks movement towards a weaponized nuclear programme, military escalation, or both.

Dr Sanam Vakil
Director, Middle East and North Africa Programme

Dr Aniseh Bassiri Tabrizi
Associate Fellow, Middle East and North Africa Programme

Chatham House

2025 is the year the Iran nuclear agreement known as the JCPOA, signed in 2015, is set to formally expire. The deal has been on life support since the US withdrew in 2018 under the first Trump administration. Efforts at reviving it, or reaching a longer and stronger agreement, have failed amid a trust deficit, US ‘maximum pressure’ policy, and geopolitical and regional crises – particularly the Gaza war. 

When the JCPOA expires, so too will the few remaining enforcement tools that allow some pressure to be exerted on Tehran – including snapback sanctions, which can be invoked by any party at the United National Security Council (UNSC).

With no JCPOA and no alternative deal, Tehran could decide to advance its nuclear programme even further. That prospect looks far more likely following a year that has seen Iran’s deterrent capability severely undermined.

Members of the Tehran-led ‘Axis of Resistance’ like Hamas and Hezbollah have been significantly weakened by their conflicts with Israel. The Iran-friendly Assad regime in Syria has collapsed. And Israeli strikes in April and October 2024, targeting Iran’s air defences, illustrated how exposed Tehran itself may be.

President Donald Trump’s new administration has further raised the stakes. As expected, the president quickly re-imposed maximum pressure sanctions in his first weeks in office. Meanwhile, Israel has been lobbying his administration to support direct strikes on Iran’s nuclear programme, creating the potential for significant military escalation.   

An urgent search for deterrence

Unsurprisingly, Iranian policymakers are now intensely debating the need to weaponize the country’s nuclear programme, although Iran’s Supreme Leader continues to stress that the country’s programme will remain peaceful.

President Pezeshkian, who came into office in August 2024, has promised Iranians sanctions relief, signalling his interest in broader negotiations with the West. 

Yet, at the same time, Iran has significantly advanced its nuclear programme: some Iranian policymakers will now view that effort as even more essential, as the only method by which the country can quickly regain some deterrent capability and provide the country with the ultimate security guarantee.

Appropriate monitoring and verification from the International Atomic Energy Agency (IAEA) have been lacking for years. But the March IAEA report stated Iran has expanded its stockpile of highly enriched uranium by a concerning 50 per cent. Additionally, Iran’s total enriched uranium inventory is now roughly 40 times the limit it agreed to under the JCPOA. 

The need for an off-ramp

This all makes 2025 a critical year, for Iran’s nuclear programme and for broader Middle East regional security. Without an off-ramp, Iran could rush to weaponize its nuclear programme, or be attacked or both.

Both these outcomes are what the ‘E3’ (France, Germany and the UK) and the EU have been working hard to avoid since 2003, when they took the lead in negotiations, mediating between the US and Tehran in an attempt to de-escalate tensions. The E3 and the EU played a critical role as bridge builders for more than a decade, in a process that eventually led to the signing of the JCPOA.

When President Trump withdrew the US from the deal in 2018, the E3 and the EU remained committed to its survival, hoping to provide enough incentives for Iran to remain compliant to its JCPOA obligations. Despite these attempts, Iran halted its compliance in 2019. Since then, escalation has been the name of the game.

Bilateral ties between Iran, and European countries have progressively worsened. Mutual trust has decreased, with tensions rising following Tehran’s transfer of lethal aid to support Russia’s war against Ukraine.

Why Israel should be wary of a strike on Iran’s nuclear programme
Even so, neither side has a better option than re-engaging, trying to rebuild trust through a verifiable, strengthened deal.

Iran now sees negotiations with the US as a de facto capitulation to Trump’s resumed maximum pressure policy – an outcome it is not willing to accept. But it does not want military escalation either, and its economy is under dire strain. What Tehran desires above all, is long-term sanctions relief, to stave off snapback sanctions and to prevent Israeli strikes.

However, if not offered an off-ramp, Tehran will likely retaliate to maximum pressure, as it did in 2019-2020, when it attacked US targets, conducted strikes against tankers off the UAE coast, and supported proxy attacks on Saudi oil facilities.

It will not be easy for the E3 and EU to devote the political will needed to the task. They are distracted by Trump’s negotiations with Russia to end the war in Ukraine, his overturning of European security architecture and by his tariff-focused trade policy.

But failing to act could create an even worse security challenge: a US Iran policy which lacks any input from Europe and, instead, potentially relies on Russia as a mediator. Iran is already opening separate talks with China and Russia to discuss nuclear issues.

Tehran has not met US officials for direct negotiations since Trump withdrew the US from the JCPOA. Trump’s public attempt in early March to reach out to Iran’s Supreme Leader, seeking a new deal while threatening military strikes, met with an equally public rebuff due to the concomitant use of maximum pressure. 

Here is where the E3 can play a role. Its representatives have already had three meetings between November 2024 and February 2025 with Iranian officials to discuss the scope and scale of direct negotiations.

European countries are therefore already well placed to re-establish their historic mediating role between Iran and the US. By building on their decades-long experience in engaging with Tehran, and finding common ground with the US, Europe can kick start fresh negotiations on a new deal. Their strong ties with Israel and the Gulf Arab states can help deliver regional buy-in to avoid the pitfalls of the past and build a more resilient deal.

A fresh round of E3 negotiations begin next week: to move existing talks beyond their current status Europe should set out a disciplined timeline to reach a deal before snapback expires, and define the scope and incentives on the table.

The E3 must act, and decisively. The alternative is a path to nuclear or military escalation that will make an already threatening European security environment even more complex, and far more unstable.