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Foreign Perspective // July 2026 // by Simon

How Trump’s 2018 decision pulled Europe into war

Despite a shaky ceasefire, US and Iranian forces are still exchanging fire in the Strait of Hormuz. Germany’s economic confidence has hit its lowest point since Covid. Chancellor Friedrich Merz says the conflict is costing Germany a lot of money.

Germany didn’t want this war. It tried to prevent it. In 2018, the German government, alongside France and the UK, fought to save the Iran nuclear deal after the US pulled out under Trump. They built workaround payment mechanisms. They argued, warned, and mediated. None of it worked. The deal collapsed because without Washington, no framework holds.

Eight years later, Germany is paying the bill for a decision made in Washington.

How did we get here? The answer doesn’t start in February 2026, when US and Israeli forces killed Khamenei. It doesn’t start in June 2025, when Operation Midnight Hammer destroyed three Iranian nuclear facilities. It starts on May 8, 2018, the day the United States unilaterally withdrew from the Joint Comprehensive Plan of Action. The JCPOA had its flaws. But it was a working institutional framework. Its loss triggered the escalation spiral that now threatens European stability.

This analysis maps the Western policy debate around that decision. It asks, „What arguments dominated?“ Along which lines did the debate organize itself? And how do those arguments hold up against the US’s own stated goals of nonproliferation and regional stability?

The thesis: the US withdrawal on May 8, 2018, systematically undermined those goals and structurally contributed to the escalation that followed.

Two voices define the debate

Two Foreign Affairs articles frame the entire discussion. Both appeared in 2018. Both are primary sources, not analysts, but decision-makers.

Wendy Sherman negotiated the JCPOA as US chief negotiator. She argues the deal worked out well. It created a framework for inspection rights, verification mechanisms, and diplomatic channels that wouldn’t have existed otherwise. The withdrawal didn’t just break a deal. It destroyed that framework.

Michael Pompeo, as Secretary of State, signed off on the withdrawal. His argument: Iran is a revisionist power. The deal didn’t contain its regional ambitions; it funded them. Only maximum pressure could produce a behavioral change.

These two positions define the poles of the debate. The other 38 texts in this corpus respond explicitly or implicitly to the question Sherman and Pompeo raised in 2018.

The case for cooperation

Colin Kahl’s October 2018 response to Pompeo remains the sharpest early critique. Before the JCPOA, Iran was two to three months from weapons-grade material. After the deal: at least twelve months. That’s not symbolic; it’s strategically significant.

Kahl also points to a paradox: sanctions may actually increase the Revolutionary Guards‘ budget through smuggling and domestic mobilization. Even under maximum pressure before 2015, Iran funded Hezbollah, Iraqi militias, and the Houthis. The money isn’t the constraint.

Ali Vaez at the International Crisis Group draws the six-year balance in January 2024. The transparency framework is gone. The IAEA has lost full access. Tehran no longer believes Western commitments are reliable. That loss of trust, Vaez argues, is a direct consequence of the 2018 withdrawal. Diplomacy is the only tool that ever actually contained Iran’s nuclear program. Military options, at best, delay it.

The Iranian perspective comes from former Foreign Minister Zarif and Amir Parsa Garmsiri writing in December 2025. Their text is Iranian foreign policy in written form, a primary source, not an analytical contribution.

They describe a self-reinforcing cycle: Iran is framed as a threat, treated as a threat, responds with escalation, and thereby confirms the threat narrative. The JCPOA broke that cycle in 2015. The withdrawal reactivated it.

The Case for containment

Carol and Jamsheed Choksy writing in October 2024, make the strongest argument against the cooperation thesis. The question, they argue, is no longer whether Iran seeks nuclear weapons but when. October 7 accelerated that calculus. Proxy networks were weakened and commanders eliminated. Nuclear weapons have shifted from a strategic option to a survival instrument.

Their blind spot: they describe Iran’s nuclear trajectory as a structural phenomenon without examining the institutional conditions under which that trajectory was measurably slowed between 2015 and 2018.

Dennis Ross takes a more honest position. Writing in September 2019, he accepts the containment logic but criticizes its execution. Economic pressure is a tool, not a goal. Without red lines and diplomatic offers, it produces counter-pressure. He documents it empirically. After the US ended sanction waivers in May 2019, Iran’s rial lost 60 percent of its value. The attack on the Abqaiq oil facility in September 2019, affecting five percent of global oil processing, was Iran’s calibrated response. Not strength. Structured pressure from a weakened position.

Ross doesn’t endorse a return to the original JCPOA. He wants a stricter deal with longer timelines. He stays within containment logic. But his empirical findings support the opposite conclusion: maximum pressure produced counter-pressure, not capitulation.

Ray Takeyh writing in 2021 goes furthest. Diplomacy is already dead, he argues. Four US presidents have prioritized the nuclear problem without result. His wager: nuclear weapons will hurt Iran more than they help. They trigger regional arms races, harden the US position, and mobilize domestic opposition. That’s not a strategy. It’s a speculation.

What unites all three: the JCPOA’s measurable achievements, verification, transparency, and breakout time go unmentioned or are treated as irrelevant.

The German perspective

The SWP corpus is smaller, eleven texts, but analytically independent. It leans heavily toward cooperation logic. Only three of eleven articles support containment. All three come from one author: Guido Steinberg.

That’s a finding in itself. In German foreign policy analysis, containment is a minority position.

The earliest text in the entire corpus appeared in February 2018 – three months before the withdrawal. Corentin Brustlein and nine co-authors from SWP, Chatham House, IFRI, and RAND warned that a US withdrawal would not just destroy the deal. It would undermine all transatlantic cooperation on nonproliferation. They described precisely what then happened. Iran approached the nuclear threshold. The international community fragmented. Effective coordination became impossible. This is a warning document, not proof. But it shows that the transatlantic consensus at the moment of withdrawal was unambiguous. The US acted against the explicit advice of its closest allies.

Azadeh Zamirirad closes the causal chain in May 2025. Iran now holds 7,464 kilograms of enriched uranium – twenty-five times the JCPOA limit. Breakout time is days. The Additional Protocol has been suspended since 2021. Zamirirad identifies May 2019 as the turning point: Iran began suspending its technical commitments as a direct response to the 2018 withdrawal. No other text in the corpus documents this chain so completely.

Steinberg’s three articles 2018, 2021, 2024 make the strongest counterargument. Iran’s proxy network ran parallel to the JCPOA. The deal didn’t stop it. Hezbollah received over a billion dollars in Iranian support during the Syria conflict. The network had more than 100,000 rockets. The deal didn’t change that.

But even Steinberg calls the withdrawal a mistake.

His 2024 text on Iran’s relationship with al-Qaeda adds a further dimension. The relationship is ideologically paradoxical. Iran is a Shia state, al-Qaeda a Sunni jihadist organization. But they share a common enemy: the United States. Iran has held senior al-Qaeda figures, released others, and allowed selective passage through its territory. In 2015, during the final phase of JCPOA negotiations, five senior al-Qaeda leaders were released. The analytical point: this shadow policy ran throughout the JCPOA period. The deal didn’t cause it, didn’t change it, and the withdrawal didn’t stop it. Nuclear policy and regional policy are separate variables. The JCPOA was designed to constrain the nuclear program. It did. The withdrawal destroyed that constraint. The regional policy continued regardless.

What the debate shows

Forty texts. Eight years. Two poles. A majority in between.

The debate leans toward cooperation, but it’s not uniform. Twenty of forty texts occupy middle ground. Ten clearly support cooperation logic. Six support containment.

The containment camp has no coherent solution. Pompeo, Choksy, Steinberg, they diagnose Iran accurately as a revisionist actor. None of them answer the central question: What exactly should pressure achieve if Iran demonstrably doesn’t capitulate? Takeyh speculates on self-harm. Ross admits pressure alone fails but can’t name an alternative.

The most striking finding: even the strongest containment voices – Steinberg in SWP, Ross in Foreign Affairs call the withdrawal a mistake. Containment logic is defended as a principle. The specific act of May 8, 2018, is defended by nobody in the corpus except its architect.

The cooperation camp has stronger empirical ground. But it can’t answer what comes next. After the Twelve-Day War, after Khamenei’s death, after the Snapback mechanism expired, what’s still possible? Haass identified a window in January 2025. It closed before it was used.

Conclusion

The thesis holds: the US withdrawal on May 8, 2018, systematically undermined America’s stated goals and structurally contributed to the escalation that followed.

That’s not proven. Causality in foreign policy is rarely clean.

Iran made its own escalation decisions that go beyond reaction. But the burden of proof lies with the containment camp. No text in the corpus demonstrates empirically that maximum pressure brought Iran closer to the desired behavioral change. The opposite is documented.

The JCPOA wasn’t a gesture of trust toward Iran. It was an institutional framework. Its loss didn’t just destroy a negotiating opportunity. It removed the structural conditions under which solutions were conceivable.

Germany is now living with the consequences of that removal.

Quellenverzeichnis

Zwischentöne

• Tabaar, Mohammad Ayatollahi. The Islamic Republic’s New Lease on Life. Foreign Affairs, 8. Juli 2025.

• Maloney, Suzanne. Iran’s Dangerous Desperation. Foreign Affairs, September/Oktober 2025.

• Grajewski, Nicole / Panda, Ankit. The Stunning Failure of Iranian Deterrence. Foreign Affairs, 19. Maerz 2026.

• Alterman, Jon B. A Detente Option for Iran. Foreign Affairs, 3. April 2024.

• Golkar, Saeid / Aarabi, Kasra. The Brewing War With Israel Is Boosting Iran’s Young Hard-Liners. Foreign Affairs, 11. Oktober 2024.

• Brewer, Eric. Iran’s New Nuclear Threat. Foreign Affairs, 24. Juni 2024. [Grenzquelle: NTI]

• Vaez, Ali. Why the War in Gaza Makes a Nuclear Iran More Likely. Foreign Affairs, 25. Januar 2024.

• Kaye, Dalia Dassa. Israel’s Dangerous Shadow War With Iran. Foreign Affairs, 27. Februar 2023.

• Ostovar, Afshon. The U.S. and Iran Are Marching Toward War. Foreign Affairs, 28. Juni 2019.

• Malkasian, Carter / Constantino, Zachary. Nuclear Powers, Conventional Wars. Foreign Affairs, 17. Juli 2025.

• Reid Smith, James. Don’t Betray America First With a War on Iran. Foreign Affairs, 18. Juni 2025.

Stiftung Wissenschaft und Politik (SWP): Analysekorpus (11 Artikel)

Pol A: Kooperationslogik

• Sascha / Meier, Oliver / Zamirirad, Azadeh. Irans Atomprogramm: Washington und Brüssel auf Kollisionskurs. SWP-Aktuell, Juli 2017.

• Brustlein, Corentin et al. Saving Transatlantic Cooperation and the Iran Nuclear Deal. SWP-Comment, Februar 2018.

• Zamirirad, Azadeh. Neue Atomgespräche mit Iran. SWP-Aktuell 22, Mai 2025.

Pol B: Eindämmungslogik

• Steinberg, Guido. Die schiitische Internationale. SWP-Aktuell, Oktober 2018.

• Steinberg, Guido. The Axis of Resistance. SWP Research Paper, August 2021.

• Steinberg, Guido. Der Nexus zwischen al-Qaida und Iran. SWP-Aktuell 9, Maerz 2024.