United States President Donald Trump has again raised the possibility of withdrawing the United States from NATO, linking the future of Washington’s role in the alliance to European governments’ refusal to support American military operations in the war with Iran.
Secretary of State Marco Rubio has struck a similar note, saying that NATO membership may need to be re-examined once the conflict ends. Trump said on 1 April that he was “absolutely” considering withdrawal, while Rubio said the administration could see a “finish line” in the Iran war but suggested that the alliance would face renewed scrutiny afterwards.
The remarks do not amount to a formal withdrawal process, but they have reopened a question that has shadowed Trump’s approach to NATO since his first term in office. His longstanding criticism has centred on burden-sharing, European defence spending, and what he sees as an imbalance between American commitments and allied support. The current dispute has given that position a new operational context: Washington is now openly complaining that several European allies would not provide the military and logistical backing the administration wanted for its campaign against Iran.European resistance included restrictions linked to airspace, bases and broader military support, further aggravating already strained transatlantic relations.
Yet the threat of withdrawal is easier to voice than to implement. Under Article 13 of the North Atlantic Treaty, a member state may leave one year after giving notice. In the United States, however, the legal position is disputed. Congress adopted legislation in late 2023, later in force as Section 1250A, stating that a president may not withdraw from NATO without either a two-thirds Senate vote or an Act of Congress. That statute was backed on a bipartisan basis by Senator Tim Kaine and, notably, Marco Rubio before he became secretary of state. Legal uncertainty remains because the US Constitution does not clearly spell out who controls treaty withdrawal, and the Supreme Court has never issued a definitive ruling on the matter. Any attempt to bypass Congress would therefore almost certainly trigger a constitutional and political battle.
Even if a formal exit proved difficult, a determined White House could still weaken NATO in practice. Analysts have pointed out that a president does not necessarily need to complete a legal withdrawal in order to damage the alliance’s credibility. A reduced American commitment to Article 5, hesitation over force posture, or a drawdown of logistics and command structures in Europe could have consequences well before any treaty process ran its course. That concern has grown after Defence Secretary Pete Hegseth declined this week to restate unequivocal support for NATO’s collective-defence obligation, instead saying the matter was for Trump to decide.
There is also a practical military question. The administration’s frustration with Europe is politically clear, but the United States still relies heavily on its European network for access, basing, transport and coordination beyond the continent, including for operations affecting the Middle East. That reality limits how far an American administration can turn its back on Europe without imposing costs on itself. European governments have made clear that NATO was created for collective defence in the Euro-Atlantic area, not to provide automatic support for a US-led war against Iran. From their perspective, refusal to join such a conflict is not a rejection of the alliance treaty itself.
Trump’s calculation may therefore be as much political as strategic. Reuters reported this week that he believes the war with Iran could be concluded within weeks and that Washington would then leave “pretty quickly” once its objectives had been met. Rubio has also projected confidence that the conflict is moving towards an end. But wars rarely conclude on the timetable announced by political leaders, and the longer the conflict continues, the more likely it is to test markets, presidential authority and domestic opinion in the United States.
For Europe, the immediate significance of Trump’s latest threat lies less in whether the United States formally leaves NATO tomorrow than in what repeated threats do to confidence in American guarantees. If allies begin to treat Washington as an unpredictable security partner, the damage may outlast the present dispute and outlast Trump himself. That is why the issue now extends beyond treaty law. It goes to the wider question of whether the United States still sees alliance leadership as a strategic asset, or increasingly as a negotiable burden to be used in wartime bargaining. Recent events suggest that, for Trump, that question remains open.
