WASHINGTON—President Trump has raised with his advisers the possibility of withdrawing from NATO if allies don’t help reopen the Strait of Hormuz, U.S. officials said, as growing tensions with Europeans threaten the alliance that has been the foundation of the post-World War II order.
He hasn’t explicitly given an order to pull the U.S. out of the alliance that has stood for more than three-quarters of a century, the officials said. But they added that Trump has discussed leaving NATO or potentially finding ways to weaken the U.S. commitment to the organization. Trump has made no final decision about the future of the U.S. role in the North Atlantic Treaty Organization, the officials said.
Trump’s comments, made recently to Secretary of State Marco Rubio and others in private conversations, come as he urges Europeans to pry open the Strait of Hormuz so the U.S. can end its military campaign against Iran. He has railed against NATO for not joining U.S.-Israeli military efforts against Iran.
When asked about Trump’s private comments, White House spokeswoman Anna Kelly said “President Trump has made his disappointment with NATO and other allies clear, and as the president emphasized, ‘the United States will remember.’”
The State Department and NATO declined to comment.
Trump’s conversations about the U.S. role in NATO come as European leaders have hardened their stances toward Trump. Polls show the Iran war is deeply unpopular among European voters. Even leaders who were once considered among the U.S. president’s closest allies have expressed growing frustration with him over the Iran conflict and his demands.
German Chancellor Friedrich Merz, who once boasted about his close relationship with Trump, said last week that he had firmly rejected the president’s demand to help open the Strait of Hormuz in a phone call between the two leaders. He said the way the U.S. president was speaking about Germany and Europe was unacceptable.
“I told him, if you wanted our help, you should have asked earlier instead of going to the newspapers now,” Merz said.
Trump and others in his administration have been publicly airing their frustrations with NATO allies. Trump told a British newspaper, the Telegraph, in an interview that he was strongly considering pulling the U.S. out of NATO.
On Fox News Tuesday, Rubio signaled that after the war Trump would rethink whether the U.S. should remain in NATO.
“Unfortunately, after this conflict has concluded, we are going to have to re-examine that relationship, we are going to have to re-examine the value of NATO and that alliance for our country,” he told host Sean Hannity. “Ultimately, that’s a decision for the president to make, and he’ll have to make it.”
A spokesman for Merz said Wednesday that Germany hadn’t received any internal signals that a big shift was coming, dismissing Trump’s rhetoric as a tactic to raise pressure on allies.
A law passed by Congress in 2023 prohibits a president from unilaterally withdrawing the U.S. from NATO. Doing so requires a two-thirds vote in the Senate or a joint act of Congress. Rubio championed the legislation when he was in the Senate.
Any move by NATO’s strongest country to exit the alliance or downgrade its relationship to the other 31 member states would deal the biggest-ever blow to the bloc. It would shake the foundation of the post-World War II order and escalate the crisis between the U.S. and Europe amid Russia’s war in Ukraine and Trump’s efforts to seize Greenland from Denmark, a NATO ally.
It would also significantly hinder the U.S. ability to carry out operations in the Middle East, given how U.S. bases in Europe provide crucial logistical and supply hubs for U.S. military missions abroad.
European military and political leaders have long said that NATO’s deterrence is based not only on its warfighting capacity, but above all on the belief by allies and adversaries alike that the alliance would stand as one if challenged.
“NATO is like a religion—you either believe it works, or you don’t, and now we have reached a stage where everyone on both sides of the Atlantic has lost their faith completely,” said Ivan Krastev, a fellow with the Institute for Human Sciences in Vienna.
Trump’s ire rose after Spain closed its airspace to U.S. planes involved in the Iran war, while France reportedly blocked Israeli planes from flying weapons it needed to restock through its airspace.
“It is absolutely true that France, which was not consulted and is not part of this military offensive launched by the United States and Israel, is not taking part in it,” French President Emmanuel Macron said Wednesday.
The Trump administration has since made no secret of its recent anger toward allies.
Trump early Tuesday morning berated allies like the U.K. and France for not getting involved in the Iran war. Defense Secretary Pete Hegseth followed suit minutes later at the Pentagon: “You don’t have much of an alliance if you have countries that are not willing to stand with you when you need them.”
Officials from allied countries countered that it is difficult to coordinate support for the U.S. from the outset when they weren’t given a heads up that Trump was launching a war. Some senior European officials have fumed privately that the war has been poorly thought out and question why Trump is pushing allies to clean up a conflict that he started.
Still, European allies have offered a crucial springboard for the U.S. to launch continued attacks against Iran. U.S. bombers, drones and ships have either launched strikes, refueled, or rearmed from various NATO countries in Europe, including the United Kingdom, Germany, Romania, Portugal, France and Greece.
The United Kingdom has allowed the U.S. to carry out long-range bombing runs on Iran with B-1 and B-52 bombers from its territory, and British jet fighters have conducted defensive patrols over Gulf countries, shooting down Iranian drones and missiles targeting U.S. allies in the region. As a result of the war, London has amassed its largest military footprint in the Middle East in the last 15 years, a senior British official said.
Earlier this month, nearly 40 countries—including the U.K., France and Canada—pledged “our readiness to contribute to appropriate efforts to ensure safe passage through the Strait.”
U.S. Air Force Gen. Alexus Grynkewich, the head of U.S. European Command and top military chief at NATO, told Congress in a hearing earlier this month that the network of U.S. alliances in Europe were crucial for the U.S. military’s ability to “project power globally.”
Allies including France, Canada, the United Kingdom and others have also signaled they could potentially support future military escort missions in the Strait of Hormuz once the fighting dies down to protect the critical maritime chokepoint for global energy trade.
NATO’s bedrock is Article V of its founding treaty, which considers an attack on one member state an attack on all. The article has only been invoked once before, when allies supported the U.S. following al Qaeda’s attacks on Sept. 11, 2001. NATO countries joined the U.S. for the wars in Afghanistan and Iraq, suffering thousands of casualties alongside American troops.
But Trump believes NATO’s absence from the Iran mission means the U.S. can’t rely on the alliance in the future.
“We spend hundreds of billions of dollars a year on NATO, hundreds, protecting them, and we would have always been there for them, but now, based on their actions, I guess we don’t have to be,” he said last week during a Miami speech.
Write to Alexander Ward at alex.ward@wsj.com, Robbie Gramer at robbie.gramer@wsj.com and Bojan Pancevski at bojan.pancevski@wsj.com