US President Donald Trump said he is considering withdrawing the United States from Nato, signalling a potential rupture in the transatlantic alliance and raising fresh uncertainty over Washington’s security commitments to Europe.

Asked by a reporter whether he was rethinking the US relationship with Nato, including “possibly getting out,” Trump replied that he was dissatisfied with the alliance’s burden-sharing arrangements, Fox News reports.

“I’m disappointed in Nato that we spend trillions of dollars on Nato,” Trump said, reiterating a long-standing complaint that European allies rely excessively on US defence spending.

He added that he could act unilaterally, stating: “I don’t need Congress for that decision.”

Trump is wrong. He does need Congress’ approval to pull the US out of Nato. A law passed by Congress in late 2023 explicitly restricts the president’s ability to exit the alliance without legislative approval. The provision, included in the National Defence Authorization Act, states that the president may not suspend, terminate or withdraw the United States from Nato without either a two-thirds majority approval in the Senate or the passage of an act of Congress.

The measure was introduced on a bipartisan basis in response to longstanding concerns about Trump’s scepticism towards Nato and was designed to reinforce Congress’s constitutional role in overseeing international agreements. Polymarket currently has the odds on the breakup of Nato at an all-time high.

The remarks are likely to alarm European capitals, where Nato is seen as the cornerstone of collective defence, particularly amid heightened tensions with Russia following its full-scale invasion of Ukraine.

The alliance’s Article 5 mutual defence clause has underpinned Western security architecture since its founding in 1949, however, the US commitment to the collective security clause began to be questioned in earnest following the Nato summit in the Hague last June. Trump threatened or ignored the US commitments to Article 5 for those countries that didn’t increase their defence spending to 5% of GDP. The weakening of US commitment was also made explicit in the new US National Security Strategy (NSS), released in December.

Trump has repeatedly criticised Nato during both his presidency and subsequent political campaigns, arguing that member states fail to meet defence spending targets. While Nato members have increased military budgets in recent years, several still fall short of the alliance’s 2% of GDP benchmark, although progress has accelerated since 2022.

Trump’s comments come in the context of his dissatisfaction with his call on Nato allies to send warships to the Gulf in his efforts to reopen the Strait of Hormuz. All of them have refused.

“I’m disappointed in Nato,” Trump said, adding that US contributions far outweigh those of its allies.