The U.S. bombing of three Iranian nuclear facilities on June 22, 2025, sent shock waves around the world. It marked a dramatic reversal for the Trump administration, which had just initiated negotiations with Tehran over its nuclear program. Dispensing with diplomacy, the U.S. opted for the first time for direct military involvement in the then-ongoing Israeli-Iranian conflict.

European governments have long pushed for a diplomatic solution to Tehran’s nuclear ambitions. Yet, the reaction in the capitals of Europe to the U.S. bombing of the nuclear facilities was surprisingly subdued.

European Commission President Ursula von der Leyen noted Israel’s “right to defend itself and protect its people.” German Chancellor Friedrich Merz was equally supportive, arguing that “this is dirty work that Israel is doing for all of us.” And a joint statement by the E3 – France, the U.K. and Germany – tacitly justified the U.S. bombing as necessary to prevent the possibility of Iran developing nuclear weapons.

Europe’s responses to the Israeli and American strikes were noteworthy because of how little they discussed the legality of the attacks. There was no such hesitation when Russia targeted civilian nuclear energy infrastructure in Ukraine in 2022.

But the timid reaction also underscored Europe’s bystander role, contrasting with its past approach on that topic. Iran’s nuclear program had been a key focal point of European diplomacy for years. The E3 nations initiated negotiations with Tehran back in 2003. They also helped to facilitate the signing of the 2015 Iran nuclear deal, which also included Russia, the European Union, China, the U.S. and Iran. And the Europeans sought to preserve the agreement, even after the unilateral U.S. withdrawal in 2018 during President Donald Trump’s first term.

As a scholar of transatlantic relations and security, I believe Europe faces long odds to once again play an impactful role in strengthening the cause of nuclear nonproliferation with Iran. Indeed, contributing to a new nuclear agreement with Iran would require Europe to fix a major rift with Tehran, overcome its internal divisions over the Middle East and manage a Trump administration that seems less intent on being a reliable ally for Europe.

Growing rift between Iran and Europe

For European diplomats, the 2015 deal was built on very pragmatic assumptions. It only covered the nuclear dossier, as opposed to including other areas of contention such as human rights or Iran’s ballistic missile program. And it offered a clear bargain: In exchange for greater restrictions on its nuclear program, Iran could expect the lifting of some existing sanctions and a reintegration into the world economy.

As a result, the U.S. withdrawal from the deal in 2018 posed a fundamental challenge to the status quo. Besides exiting, the Trump White House reimposed heavy secondary sanctions on Iran, which effectively forced foreign companies to choose between investing in the U.S. and Iranian markets. European efforts to mitigate the impact of these U.S. sanctions failed, thus undermining the key benefit of the deal for Iran: helping its battered economy. It also weakened Tehran’s faith in the value of Europe as a partner, as it revealed an inability to carve real independence from the U.S.

After 2018, relations between Europe and Iran deteriorated significantly. Evidence of Iranian state-sponsored terrorism and Iran-linked plots on European soil hardly helped. Moreover, Europeans strongly objected to Iran supplying Russia with drones in support of Moscow’s invasion of Ukraine – and later on, ballistic missiles as well. On the flip side, Iran deeply objected to European support for Israel’s war in the Gaza Strip in the aftermath of the Oct. 7, 2023, attacks.

These deep tensions remain a significant impediment to constructive negotiations on the nuclear front. Neither side currently has much to offer to the other, nor can Europe count on any meaningful leverage to influence Iran. And Europe’s wider challenges in its Middle East policy only compound this problem.

Internal divisions

In 2015, Europe could present a united front on the Iranian nuclear deal in part because of its limited nature. But with the nonproliferation regime now in tatters amid Trump’s unilateral actions and the spread of war across the region, it is now far harder for European diplomats to put the genie back in the bottle. That is particularly true given the present fissures over increasingly divisive Middle East policy questions and the nature of EU diplomacy.

Europe remains very concerned about stability in the Middle East, including how conflicts might launch new migratory waves like in 2015-16, when hundreds of thousands of Syrians fled to mainland Europe. The EU also remains very active economically in the region and is the largest funder of the Palestinian Authority. But it has been more of a “payer than player” in the region, struggling to translate economic investment into political influence.

In part, this follows from the longer-term tendency to rely on U.S. leadership in the region, letting Washington take the lead in trying to solve the Israeli-Palestinian conflict. But it also reflects the deeper divisions between EU member nations.

With foreign policy decisions requiring unanimity, EU members have often struggled to speak with one voice on the Middle East. Most recently, the debates over whether to suspend the economic association agreement with Israel over its actions in Gaza or whether to recognize a Palestinian state clearly underscored the existing EU internal disagreements.

Unless Europe can develop a common approach toward the Middle East, it is hard to see it having enough regional influence to matter in future negotiations over Iran’s nuclear program. This, in turn, would also affect how it manages its crucial, but thorny, relations with the U.S.

Europe in the shadow of Trump

The EU was particularly proud of the 2015 nuclear deal because it represented a strong symbol of multilateral diplomacy. It brought together great powers in the spirit of bolstering the cause of nuclear nonproliferation.

Ten years on, the prospects of replicating such international cooperation seem rather remote. Europe’s relations with China and Russia – two key signers of the original nuclear deal – have soured dramatically in recent years. And ties with the United States under Trump have also been particularly challenging.

Dealing with Washington, in the context of the Iran nuclear program, presents a very sharp dilemma for Europe.

Trying to carve a distinct path may be appealing, but it lacks credibility at this stage. Recent direct talks with Iranian negotiators produced little, and Europe is not in a position to give Iran guarantees that it would not face new strikes from Israel.

And pursuing an independent path could easily provoke the ire of Trump, which Europeans are keen to avoid. There has already been a long list of transatlantic disputes, whether over trade, Ukraine or defense spending. European policymakers would be understandably reticent to invest time and resources in any deal that Trump could again scuttle at a moment’s notice.

Trump, too, is scornful of what European diplomacy could achieve, declaring recently that Iran doesn’t want to talk to Europe. He has instead prioritized bilateral negotiations with Tehran. Alignment with the U.S., therefore, may not translate into any great influence. Trump’s decision to bomb Iran, after all, happened without forewarning for his allies.

Thus, Europe will continue to pay close attention to Iran’s nuclear program. But, constrained by poor relations with Tehran and its internal divisions on the Middle East, it is unlikely that it will carve out a major role on the nuclear dossier as long as Trump is in office.

Garret Martin receives funding from the European Union for the organization, the Transatlantic Policy Center, that he co-directs.