BRUSSELS: The NATO alliance has faced existential challenges in recent years, from the war in Ukraine to repeated pressure and criticism from U.S. President Donald Trump, who has questioned the alliance’s core mission and even threatened to seize Greenland.
However, analysts and diplomats now warn that the U.S.-Israeli war with Iran, thousands of miles from Europe, poses the gravest threat yet to the 76-year-old bloc, potentially leaving it in its weakest state since its founding.
Trump, frustrated that European nations have declined to deploy their navies to secure the Strait of Hormuz following the start of the air war on February 28, has indicated he is considering withdrawing from the alliance.
“Wouldn’t you if you were me?” Trump told Reuters in a Wednesday interview.In a speech the same night, Trump criticized U.S. allies but stopped short of formally condemning NATO, as many experts had expected.
Nevertheless, combined with other recent barbs directed at European countries, his comments have sparked unprecedented concern that the U.S. may not defend its NATO allies if they are attacked—even without a formal exit from the alliance.
Analysts say this threatens the core of NATO, the mutual defense agreement that has long underpinned European security. Max Bergmann, a former State Department official and now head of the Europe, Russia, and Eurasia Program at the Center for Strategic and International Studies, called the situation “the worst place NATO has been since it was founded,” adding, “It’s really hard to think of anything that even comes close.”
The reality is setting in for Europeans, who have historically relied on NATO as a safeguard against an increasingly assertive Russia. As recently as February, NATO Secretary-General Mark Rutte dismissed the idea of Europe defending itself without U.S. support as “a silly thought.”
Now, many officials view it as a default expectation.General Francois Lecointre, France’s former armed forces chief from 2017 to 2021, said, “NATO remains necessary, but we must be capable of thinking of NATO without the Americans. Whether it should even continue to be called NATO—North Atlantic Treaty Organization—is a valid question.”
White House spokeswoman Anna Kelly stated, “President Trump has made his disappointment with NATO and other allies clear, and as the President emphasized, ‘the United States will remember.’” A NATO representative did not immediately respond to requests for comment.
NATO has faced challenges before, particularly during Trump’s first term from 2017 to 2021, when he also considered withdrawal. While Europeans previously believed Trump could be placated with diplomacy and flattery, that belief has waned, according to multiple U.S. and European officials.
Trump and his team have expressed frustration over what they see as NATO’s unwillingness to assist the U.S., including with the Strait of Hormuz, and restrictions on U.S. use of certain airfields and airspace. U.S. officials have stressed that NATO cannot be a “one-way street.”
European officials counter that no formal requests were made for assistance, and Washington has been inconsistent about whether such missions would take place during or after the conflict.Jamie Shea, a former senior NATO official and now senior fellow at the Friends of Europe think tank, said, “It is a blow to the allies who, since Trump returned to the White House, have worked hard to show that they are willing and able to take more responsibility for their own defense.”
Other signs of strain include Trump’s January threats to seize Greenland from Denmark and U.S. actions perceived as accommodating toward Russia, which NATO considers its principal security threat. Reports indicate Moscow has provided targeting data to Iran for attacks on U.S. assets in the Middle East, and sanctions on Russian oil have been lifted to ease global energy costs during the war.
Tensions were further highlighted at a recent G7 foreign ministers’ meeting near Paris, where U.S. Secretary of State Marco Rubio and EU foreign policy chief Kaja Kallas had a tense exchange. Kallas questioned U.S. patience with Russian President Vladimir Putin over Ukraine peace talks, prompting Rubio to stress that the U.S. was trying to end the war while supporting Ukraine, leaving the EU free to mediate if it wished.
Legally, Trump may lack the authority to withdraw from NATO, as a 2023 law requires two-thirds of the Senate to approve any exit—a nearly impossible threshold. However, analysts note that as commander-in-chief, Trump can decide whether the U.S. military will defend NATO members, potentially jeopardizing the alliance without a formal exit.Not everyone considers the crisis existential.
One French diplomat described Trump’s rhetoric as a passing temper tantrum. Trump has previously changed his NATO position; in 2024, he suggested on the campaign trail that he might encourage Putin to attack NATO members who fail to meet defense spending targets. By June 2025, NATO was once again in his good graces, with Trump praising European leaders at the annual summit.
Next week, Secretary-General Mark Rutte is set to visit Washington to try to recalibrate Trump’s stance once again. Analysts note that European nations have strong incentives to keep the U.S. engaged in NATO, citing irreplaceable military capabilities such as satellite intelligence.
Even if Trump and European leaders restore cooperation, diplomats and officials warn that the transatlantic alliance, central to global order since World War Two, may never return to its previous form.
Julianne Smith, U.S. ambassador to NATO under President Joe Biden, said, “We’re turning the page of 80 years of working together. It doesn’t mean the end of the transatlantic relationship, but we’re on the cusp of something that’s going to have a different look and feel to it.”