BRUSSELS

A growing dispute over the war in Iran is exposing deep divisions between the US and NATO, raising fresh questions about whether the alliance can hold together under pressure.

As US President Donald Trump urges European allies to support military efforts to reopen the Strait of Hormuz, several key NATO members are pushing back, highlighting differences not just over strategy, but also over the very purpose of the alliance.

Analysts say the rift reflects a broader shift in transatlantic relations that has been building for years and could deepen if the conflict in Iran drags on.

“This is the same Trump pattern: take unilateral actions without including allies, then bully them into supporting that action. Trump understands allies’ fear of NATO evaporating, and presses this sensitivity to extract advantage whenever he can,” said Daniel Hamilton, a senior fellow at Johns Hopkins’ SAIS Foreign Policy Institute and the Brookings Institution.

“Much of this is bluster. It is not a turning point. European trust in Trump vanished long ago,” he added.

Yet others warn that the current dispute carries real risks.

“There is no question that this latest dispute over whether Europe can contribute to the defense of shipping … comes on the heels of a very stressful and difficult year in transatlantic relations,” said Ian Lesser of the German Marshall Fund.

“There’s a very real risk that the Trump administration would take this as an opportunity to send very strong negative signals about NATO,” he said.

Europe pushes back

Trump has called on NATO allies to contribute naval forces, including escort vessels and minesweepers, to secure the Strait of Hormuz, framing the request as a test of alliance solidarity.

“It would be very bad for the future of NATO” if European countries failed to respond, he said last week.

“I’ve been saying for years that if we ever did need them, they won’t be there,” he added.

At the same time, he struck a contradictory tone, insisting that “we don’t need anybody” and describing the US as “the strongest nation in the world.”

European governments, however, have been reluctant to get involved in a conflict they did not initiate.

German Defense Minister Boris Pistorius was blunt: “It is not our war. We did not start it.”

German Chancellor Friedrich Merz echoed that position, emphasizing NATO’s defensive role and questioning whether involvement in Iran would fall within its mandate.

The UK has also resisted, with Prime Minister Keir Starmer saying Britain “will not be drawn into a wider war” and stressing that any military action would require a clear legal basis.

Spain has taken an even firmer stance, calling the war “illegal” and refusing to allow US forces to use jointly operated bases for strikes on Iran.

At the alliance level, NATO Secretary General Mark Rutte has tried to strike a more neutral tone, saying members agree the strait must reopen but are still discussing how best to respond.

A deeper divide

For many analysts, the dispute is not just about Iran and reflects deeper disagreements over NATO’s role.

Hamilton said European debates have historically focused on defending NATO territory, not joining US-led operations outside the alliance’s core area.

“That debate, until now, has focused on what NATO’s European allies should do when they are threatened. It has not yet turned to what they should do regarding ‘out of area’ contingencies – a theme that has often been a source of US-European divisions over many administrations,” he said.

Lesser said European hesitation is also shaped by concerns “that they would be dependent on a strategy they did not shape and do not control.”

The dispute also comes at a sensitive time, ahead of the 2026 NATO Summit to be held in Türkiye’s capital Ankara this July.

While Trump has repeatedly questioned the value of NATO and suggested the US could reconsider its role, Lesser said he “would not predict any radical shifts in American membership or participation,” noting strong support for the alliance in the US Congress.

Still, he warned that the tone of current disagreements could have lasting effects.

‘Getting back to the same page is going to be difficult’

The war in Iran is also exposing competing priorities within the alliance.

Dimitris Tsarouhas, a professor at Georgetown University, said European governments are concerned the conflict is distracting from their top security priority, Ukraine.

He noted that the conflict is also “deeply unpopular” among European publics due to its knock-on impact on inflation and cost of living.

Another factor, he emphasized, is that the US “did not inform or consult with its NATO allies prior to launching operations,” adding to frustration in European capitals.

How far the rift widens may depend on how long the war continues, according to Tsarouhas.

“Should it come to a prolonged conflict with an inconclusive result and economic hardship piles up, all bets are off,” he said.

For now, European leaders appear determined to avoid direct involvement, while maintaining political support for the alliance.

“Leaders will keep on dragging their feet for as long as they can afford it, and support to Washington is likely to have more of a symbolic than a truly operational character,” he said.

At the same time, US priorities appear to be shifting.

Hamilton said Washington is moving away from being “comprehensively engaged in the political, economic, and security life” of Europe, and will be more “selectively engaged” going forward.

The US could also be “tempted to play Europeans off against one another to eke out marginal short-term advantages on issues the Trump administration believes are important,” he said.

This approach, he added, has implications beyond Iran, including for Ukraine: “He is doing nothing to help Ukraine achieve victory … Ukraine’s future will be decided in Europe, not in the US.”

Analysts say that while tensions between the US and Europe are not new, pointing to past disagreements over Iraq, Vietnam and the Suez Crisis, the current moment may be different.

“What seems clear is that the US and Europe have different priorities, and coordination between them has become much more complicated than it used to be,” Tsarouhas said.

“Getting back to the same page is going to be difficult – after all, there is no agreement anymore as to what exactly NATO stands for.”​​​​​​​