Trump’s NATO Exit Threat Highlights Limits of European Power

By Tatsuya Seto ’28

On Wednesday, April 1, President Donald Trump told The Telegraph that he is weighing a US exit from the North Atlantic Treaty Organisation (NATO), a mutual defence alliance against Soviet expansion that was first established in 1949 in Washington, D.C.. Since the start of the Iran conflict, Trump has expressed his frustration with U.S. allies amidst a compromised Strait of Hormuz. The maritime passageway, which is responsible for 20 percent of the world’s oil and liquefied natural gas flow, remains largely closed off, pushing energy prices and generating fears of inflation globally. According to NBC News, the UK, China, Japan, Canada, Australia, and Germany initially declined to send in their naval forces after the President’s call-to-action.

In light of these refusals, Trump has not asked NATO and the European Union for help, accusing them of disloyalty and demanding that allies reopen the Strait without US support. According to Trump, he has always had concerns over NATO’s credibility, and the Iran conflict has seemingly pushed his criticisms to a breaking point. Trump reinforced his belief that the alliance failed to provide reciprocal support when the U.S. required it most. According to the National Defense Authorization Act (NDAA), although he declared the withdrawal as a decision that was “beyond reconsideration,” Trump faces a logistical challenge: the need for congressional approval. Despite this constraint, legal ambiguity remains over whether a president could attempt to circumvent Congress by invoking executive authority over treaty withdrawal, potentially triggering a prolonged constitutional debate to be looked over by the Supreme Court. Yet analysts argue that a formal withdrawal may not be necessary to diminish the alliance’s credibility. Even without leaving NATO, repeated threats against Europe risk undermining the trust that underpins collective defence against shared threats among Russia, China, and North Korea. As David Cattler, a senior fellow from the Center for European Policy Analysis, noted, “The real question isn’t whether the US leaves NATO, it’s whether the allies continue to trust the US to lead. [Because] alliances break when trust erodes.” For Europe, this erosion is particularly concerning as the continent’s security structure has long relied on American leadership and deterrence.

Indeed, recent tensions have already raised doubts about Washington’s commitment to NATO’s core Article 5 guarantee, with officials’ warning that uncertainty alone could weaken the effectiveness of the alliance. The EU has continued to emphasise unity, but this dispute has already exposed how dependent the bloc remains on U.S. military coordination, logistics, and nuclear deterrence. In this sense, the credibility of NATO does not hinge solely on formal membership, but also on the perceived reliability of U.S. support.

According to Reuters, this uncertainty has prompted European officials to reassess their own strategic posture. The alliance may be facing one of its most serious internal strains since its creation, with repeated US threats fueling concern that the credibility of collective defence could weaken even without a formal withdrawal. European diplomats have also acknowledged that the debate itself forces governments to consider whether they could ensure their own security independently, a scenario that would have been regarded as unlikely if it were 2 months ago.

At the same time, the possibility of a more independent NATO may signal a need for Europe to shift toward greater regional responsibility. Finland’s president, Alexander Stubb, recently described the emergence of a “more European NATO,” suggesting that European leaders have already started to visualise European states assuming larger roles within the alliance as uncertainty around US commitment grows. While these remarks and possible preparations show adaptation to damage from Donald Trump’s threats, they still underscore the extent to which transatlantic security has traditionally relied on the US, which provides many of NATO’s military logistics, including a nuclear umbrella ensured by the US’s tremendously large nuclear arsenal, military bases, and intelligence. Without this foundation, Europe’s independent military capacity remains limited, especially against close concerns like Russia.

As most European NATO members lack long-range power, nuclear deterrence independent of Washington, and a collective European defence spending that is unified under a single operational command rather than fragmented across national militaries, the credibility of European geopolitical influence continues to depend heavily on US backing. Trump’s aggressive “America First” foreign policy has not only threatened institutional change but also exposed structural imbalances for Europe, suggesting that Europe’s global power has increasingly rested on the now-precarious stability of transatlantic leadership.