Atlantic Alliance

Trump threatens to leave NATO: how he can do it and what would happen

The path out of the Atlantic Treaty is complex and the president cannot decide alone. Without the US, the alliance would lose 60% of the budget

by Massimo De Laurentiis

2 April 2026

Il presidente degli Stati Uniti Donald Trump partecipa a una conferenza stampa al termine del vertice NATO all'Aia, nei Paesi Bassi, il 25 giugno 2025. EPA/Robin van Lonkhuijsen EPA

3' min read

Translated by AI

Versione italiana

3' min read

Translated by AI

Versione italiana

After the Israeli-American attack on Iran, US President Donald Trump returned to attacking NATO, going so far as to threaten the US exit from the Atlantic Alliance. This is not the first time that Trump has criticised NATO, which the tycoon considers a useless burden for the US, which is its largest financier. The US president said he was "disgusted" by the allies, who he called "cowards" especially after their refusal to participate in a military coalition to reopen the Hormuz Strait, and called NATO "a paper tiger". In this context, the White House threat seems more concrete than ever.

The process of leaving NATO

In practice, however, pulling out is a complex process for Washington. On paper, the treaty states that any member can leave NATO with one year's notice. And here there is a first anomaly: the notification to initiate this procedure must be delivered to the US government, the original promoter and guarantor of the Atlantic pact, which in this case would find itself in the paradoxical position of having to notify itself.

Apart from this formal curiosity, the biggest difficulties are on the domestic front. In 2024, in fact, the Biden administration passed the National Defense Authorization Act, which prevents the president from making such a decision alone. According to the law, an exit from NATO requires an affirmative vote of two-thirds of the Senate, or authorisation through a act of Congress.

In addition, the president must consult with the House and Senate Foreign Affairs Committees 'in relation to any initiative to withdraw the United States' from the alliance, and must notify the committees of 'any deliberations or decisions' on withdrawal 'as soon as possible, and in no case later than 180 days before undertaking the process'.

A difficult process to complete before the midterm elections in November 2026, which could leave the Republicans with an even less solid majority in the Senate. Should Trump find a way around the ordinary procedure, a dispute with the Supreme Court, which has already recently rejected the tycoon's tariffs, cannot be ruled out. In any case, US legislation has some grey areas on this issue and the exceptional nature of the situation makes predictions difficult.

Nelle mente di Trump e Netanyahu

What the Atlantic Treaty provides for

The founding treaty of NATO itself contains a few points at odds with Trump's policies. Firstly, the famous Article 5, the heart of the treaty, provides for allied intervention in defence of a member under attack, but not military support for an aggression initiated by an alliance country.

Furthermore, the articles of the understanding explicitly refer to the UN Charter, bind members to resolve international disputes peacefully, and call for the promotion of cooperation in economic matters. All points of fact already challenged by the US administration, which in January 2026 also created a Board of Peace not bound by the prescriptions of other international organisations.

The US role in NATO

A possible US exit does not automatically mean the end of NATO, but in the immediate future it would have a great impact on the security of allies, especially the Europeans. Washington contributes 60% of NATO's total budget ($980 million), while Canada and the countries of the old continent together cover the remaining 40% ($657 million).

The substantial American military presence in Europe was a pillar of deterrence during the Cold War, and in total there are about 90,000 US soldiers on the continent, deployed on more than 40 bases. Moreover, NATO has guaranteed the American nuclear shield to Western allies for decades, and the US contribution to the alliance's missile defence system is crucial.

Italy's General Leonardo Tricarico, former Chief of Staff of the Air Force, expressed concerns about a possible American withdrawal. "If the US were to withdraw from NATO, there are two main factors that would be missing,' said Tricarico. 'The first and most important is the command and control capability, because you have to know how to wage war and Europe does not know how to wage war. The second is intelligence, because not having an effective one would mean having a blind instrument'.