Without the US, Is NATO in Ruins? Trump's Withdrawal Threat Strategy

President Donald Trump has once again rattled the foundations of the Western world's most consequential military alliance — but how serious is the threat, what does the law actually say, and what would a US exit really mean for global security?

A Threat That Shook Seventy-Seven Years of History

On April 1, 2026, President Donald Trump told the British newspaper The Daily Telegraph that American membership in NATO was "beyond reconsideration" — and not in a reassuring way. In one of the most direct attacks on the alliance any sitting US president has ever made, Trump declared he was "absolutely" considering withdrawing the United States from the very partnership it helped architect in the aftermath of World War II.

"I would say [it's] beyond reconsideration. I was never swayed by NATO. I always knew they were a paper tiger, and Putin knows that too, by the way," Trump told the publication, with a candour that alarmed capitals from London to Warsaw.

The comments did not emerge in a vacuum. They came as the Iran war — launched by the US and Israel on February 28, 2026 — continues to reshape the global order, with NATO allies largely refusing to join combat operations and Europe scrambling to address the economic fallout from the closure of the Strait of Hormuz.

A Brief History of the Alliance Trump Now Threatens to Leave

To understand the gravity of Trump's words, it helps to remember how NATO came into being and what it has meant for eight decades of Western security.

The North Atlantic Treaty Organization was founded on April 4, 1949, in the shadow of World War II and the emerging threat of Soviet expansionism. Its founding twelve members — including the United States, the United Kingdom, France, Canada, and several Western European nations — signed a collective defense treaty in Washington, D.C., built on a simple but revolutionary principle: an attack on one is an attack on all, enshrined in Article 5 of the treaty.

The alliance's founding was driven, in large part, by the United States, which recognized that a stable, unified Europe was both a moral obligation and a strategic necessity. As former Secretary of State Dean Acheson, one of NATO's chief architects, once said: "The North Atlantic Treaty is not directed against any nation or any group of nations. It is directed against armed attack."

Over the decades, NATO expanded from its original twelve members to thirty-two, incorporating former Soviet bloc nations and surviving the end of the Cold War, the September 11 attacks — which triggered the only invocation of Article 5 in history — and Russia's invasion of Ukraine. For more than three-quarters of a century, it remained the cornerstone of Western security architecture, with the United States as its undisputed anchor.

"NATO is probably the most effective alliance in history," Senate Majority Leader John Thune (R-SD) told the Washington Examiner this week — a sentiment shared across party lines and a reflection of just how deeply embedded the alliance remains in American strategic thinking.

What Sparked Trump's Latest Threat

The immediate trigger is the Iran war. European allies view the US campaign against Iran as a war of choice — one they were not consulted on in advance. Trump has lambasted NATO allies for their reluctance to get involved in US-Israeli operations, while European nations have pushed back, insisting that policing a conflict they had no hand in starting is not what collective defense means.

Secretary of State Marco Rubio has also questioned the alliance's value, arguing that if NATO is simply about the US defending Europe when attacked, but allies deny the US basing rights when Washington needs them, "that's not a very good arrangement."

Trump framed the standoff in deeply personal terms. "We've been there automatically, including Ukraine. Ukraine wasn't our problem. It was a test, and we were there for them, and we would always have been there for them. They weren't there for us," he told The Telegraph.

The White House has backed up the president's frustration publicly. White House spokesperson Anna Kelly stated that "President Trump has made his disappointment with NATO and other allies clear, and as the President has emphasized, 'the United States will remember.'"

Can Trump Actually Pull the US Out of NATO?

Here is where the threat collides with political and legal reality — and the answer is more complicated than a presidential declaration alone can resolve.

The Legal Guardrail

Legislation now in force — passed with bipartisan backing in December 2023 — requires either a two-thirds Senate vote or a separate act of Congress before any president can withdraw the United States from NATO. The law also blocks federal funding from being used to facilitate a withdrawal that lacks that approval.

Ironically, one of the co-authors of that legislation is Marco Rubio himself — now Trump's Secretary of State and one of the voices questioning the alliance's value.

Trump's Counter-Argument

The president is not unaware of this obstacle. Trump has said he could "work with some very smart people" should he decide to exit NATO, and directly claimed: "I don't need Congress for that decision, as you probably know. I can make that decision myself."

Legal experts are divided. Curtis Bradley, a distinguished service professor of law at the University of Chicago, told TIME that Trump could seek to invoke presidential authority over foreign policy to circumvent Congress's statutory constraint — an approach he has floated before — though it remains unclear whether any party would have legal standing to challenge such a move in court.

"The very idea of a U.S. exit erodes trust, cohesion, and the credibility of collective defense," said legal scholar Gioia, emphasizing that even the suggestion of departure causes enormous institutional damage — regardless of whether the threat is ever carried through.

The One-Year Clock

Even if Trump somehow bypassed Congress and filed formal withdrawal proceedings, the timeline is not immediate. Under the terms of the NATO treaty itself, a member state must issue a formal "notice of denunciation," after which its membership does not officially end until a one-year waiting period has elapsed.

As one constitutional law scholar put it: "The Supreme Court will have to resolve it within a year."

Congress Pushes Back — From Both Sides

What is striking about the bipartisan response is that it cuts across the normal partisan fractures of contemporary American politics.

Senate Majority Leader John Thune — a Republican and a Trump ally on many issues — was categorical: "Yeah, absolutely, I don't think you can make that kind of a decision unilaterally. Congress is definitely — on something like that, there isn't any question Congress is gonna want to be heard from."

Thune described NATO as an institution senators are "heavily invested" in and noted that the alliance had historically served as an essential bulwark against Russian expansion — a role that has become even more pressing since Moscow's invasion of Ukraine.

British Prime Minister Keir Starmer, asked to respond to Trump's remarks, was measured but firm. He called NATO "the single most effective military alliance the world has ever seen" and reiterated that Britain would not be "dragged into" the Iran war — but stressed the UK's unwavering commitment to the alliance and the collective defense principles underpinning it.

What a US Exit Would Actually Mean

The consequences of a genuine American withdrawal from NATO — however unlikely — would be seismic.

Russia, already emboldened by Western disunity over Iran, would find its strategic window considerably widened. The Baltic states, Poland, and other eastern members who joined NATO specifically for protection against Moscow would be left in an extraordinarily vulnerable position. Defense budgets across Europe, already under pressure, would need to expand dramatically and rapidly.

Beyond the military dimension, a US exit would call into question federal acquisition and export control authorities that simplify commercial transactions involving NATO nations, as well as the status of NATO visas for officials, staff, and their families — the invisible scaffolding of an alliance that has shaped Western commerce, intelligence sharing, and diplomatic architecture for generations.

As foreign policy analyst Richard Haass once observed, alliances are not simply military instruments — they are the institutionalised expression of shared values and mutual interests accumulated over decades. Dismantling them is far easier than rebuilding them.

The Bigger Picture: Leverage or Sincerity?

A key question hanging over all of this is whether Trump's NATO threats represent genuine strategic intent or a pressure campaign designed to extract concessions from allies reluctant to commit to the Iran war effort.

Analysts suggest Trump's frustration is tied not only to European non-participation in Iran but also to domestic political pressure, as soaring energy prices erode his approval ratings. His NATO threats, they argue, may be partly aimed at shifting blame onto allies he portrays as disloyal.

That interpretation has historical precedent. Trump threatened NATO repeatedly during his first term, demanded allies raise defense spending to 2% of GDP, and yet the alliance endured. Many European capitals are betting — cautiously — that this moment follows a similar pattern.

But the context in 2026 is materially different. The Iran war has not merely strained NATO relationships; it has exposed a genuine philosophical rupture over what collective defense means — and who decides when to invoke it.

Conclusion: Damaged, Not Destroyed — Yet

NATO is not in ruins. The legal barriers to American withdrawal are real and formidable. Congressional support for the alliance remains broad, bipartisan, and deeply felt. And even Trump's most hawkish advisors understand that leaving NATO entirely would hand Vladimir Putin the single greatest strategic gift of the twenty-first century.

But the damage being done by this moment — to trust, to deterrence, to the credibility of mutual defense commitments — is not hypothetical. It is happening in real time, in the calculations being made in Moscow, in Beijing, and in the chancelleries of allies who are quietly beginning to plan for a world where American security guarantees carry an asterisk.

The alliance that Harry Truman helped build to prevent another world war was never meant to be transactional. Whether it can survive an era in which it is treated as one remains the defining question of the age.

This article is based on verified reporting and official statements. All quotations are attributed to named public figures and on-record sources.