The NATO alliance is fracturing along lines that no amount of diplomatic polish can conceal. Trump’s refusal to consult allies before launching the US-Israeli war on Iran, followed by his public statement that he is considering withdrawing from NATO, has pushed the 77-year-old alliance into what multiple analysts describe as its worst crisis ever. The question now is not whether NATO will be damaged, but whether what replaces it can protect Europe in time. My assessment, after speaking with analysts and reviewing the available evidence, is that the alliance as it has existed since 1949 is already functionally over — and that the European project to build something workable in its place is real but dangerously behind schedule.

Jim Townsend, adjunct senior fellow at the Center for a New American Security, has described the current situation as unprecedented in its severity.

The Iran War as Catalyst

The proximate cause of the crisis is straightforward. Trump launched the war on Iran on February 28 alongside Israeli Prime Minister Benjamin Netanyahu, without consulting NATO allies and without invoking Article 5 of the Washington Treaty. He then demanded those same allies join the fight and help reopen the Strait of Hormuz after Tehran closed it in retaliation. None of Washington’s traditional partners came forward. Some European allies declared the US-Israeli attack illegal and several withheld overflight rights and base access.

Trump responded by calling European allies “cowards” and reportedly criticized the UK’s military capabilities in harsh terms.

UK Prime Minister Keir Starmer dismissed the attacks, restating that Britain would not participate in the conflict. But the diplomatic temperature has dropped well below noise.

Secretary of State Marco Rubio, who was once a staunch NATO supporter in the Senate, has questioned whether the alliance still serves US interests.

What Trump Can Actually Do

The legal barriers to a formal US withdrawal are real but far from reassuring. In 2024, Congress passed the National Defense Authorization Act with a provision, co-sponsored by Rubio himself, prohibiting a US president from unilaterally withdrawing from NATO without a two-thirds Senate majority or an act of Congress. The NDAA also bars federal funds from being used to facilitate a withdrawal.

Any attempt to formally leave would almost certainly trigger a constitutional crisis and land before the Supreme Court. But the Court has a pattern of siding with the executive on foreign policy disputes.

The deeper problem is that formal withdrawal is not necessary to gut the alliance. Stefano Stefanini, former Italian ambassador to NATO, has noted that merely threatening withdrawal damages alliance credibility.

Ivo Daalder, who served as the US permanent representative at NATO headquarters from 2009 to 2013, laid out the mechanics plainly. Trump can withdraw troops. He can pull US personnel from NATO’s command structure. He can simply do nothing if an ally is attacked. All of that is perfectly legal, and none of it requires a Senate vote.

There are roughly 84,000 American troops deployed across Europe. The Wall Street Journal has reported that Trump is considering moving some US bases from countries he deems unhelpful during the Iran war. That kind of selective punishment would fracture alliance solidarity without any Senate vote.

The Trust Problem

Military alliances run on trust. NATO invoked Article 5 for the first and only time after September 11, 2001. Nearly 500 British servicemembers died in the Afghanistan war that followed. Dozens more from France, Denmark, Italy, and other nations gave their lives in that campaign. The alliance delivered when the US needed it.

The expectation that this commitment would be reciprocal has been the bedrock of European security planning for three-quarters of a century. When Trump has expressed strongly negative views about NATO, he is not just insulting allies. He is dissolving the psychological foundation on which collective defense rests.

Nathalie Tocci, professor at the Johns Hopkins School of Advanced International Studies Europe, pointed out that this is not new behavior, just its most extreme expression. Trump’s approach represents a sustained pattern of hostility toward Europe, and European leaders are now fundamentally changing how they deal with Washington as a result.

The Russian Clock

The urgency of the crisis is not abstract. German defense estimates suggest Russia may have reconstituted its forces sufficiently to attack NATO territory by 2027 to 2029. General Carsten Breuer, Germany’s chief of defense, has warned that the threat could materialize by 2029. Other assessments put the danger as early as 2027.

Russia is already spending more on defense than the whole of Europe combined, according to The Military Balance. Pete Hegseth, Trump’s defense secretary, has demanded that NATO allies increase spending to 5% of GDP, a figure that would be politically and fiscally impossible for most European economies.

Hegseth told European allies that Washington expects greater burden-sharing and insisted Europe must provide the bulk of future aid to Ukraine. He also described Ukraine’s pre-2014 borders as unattainable and downplayed the prospect of Ukraine joining NATO, positions that will comfort Moscow far more than Kyiv.

This is the strategic context in which Europeans must now plan. The threat is on a timeline measured in months and years, not decades.

Can Europe Fill the Gap?

European defense spending increased by more than 62% between 2020 and 2025. That is a significant acceleration. But the International Institute for Strategic Studies has estimated it would take a decade or more and approximately $1 trillion to replace key elements of US conventional military capabilities in Europe.

The gaps are specific and severe. Europe lacks deep-strike capabilities, the kind of long-range precision missiles that would be needed in any serious conflict with Russia. Intelligence, surveillance, and reconnaissance assets remain heavily dependent on US platforms. Space-based capabilities are thin. Integrated air and missile defense has enormous holes.

The IISS published a strategic dossier documenting both the progress European nations have made and the shortfalls that remain. The picture is one of real momentum but inadequate scale. You cannot close a trillion-dollar capability gap by spending more on the same things at the same pace.

Finland’s President Alexander Stubb told Trump during a phone call this week that NATO was evolving with greater European responsibility. Whether that is accurate or aspirational depends on how you measure it.

A Different Kind of Alliance

Some analysts see a path forward. Minna Alander has argued that NATO could survive even major US disengagement because European members have strong incentives to maintain the alliance’s command architecture, interoperability standards, and institutional knowledge — structures that have value independent of US participation.

Ruth Deyermond, senior lecturer at King’s College London’s department of war studies, took a harder view. The problem of undervaluing NATO and taking allies for granted extends beyond the current administration, she warned, and her prescription was stark: Europeans and Canada need to develop a new security framework, despite the difficulty and expense involved.

The two perspectives are not necessarily contradictory. NATO could persist as a legal and institutional structure while its functional center of gravity shifts to Europe. But a European-led NATO without American power projection, intelligence capabilities, and nuclear deterrence would be a fundamentally different thing. It would be an alliance defined less by what it can do and more by what it intends to become.

What the Psychology of Alliance Tells Us

Alliances are not just military arrangements. They are trust architectures, systems where each member’s willingness to sacrifice for others is the core resource. When that willingness becomes questionable, the alliance does not collapse in a single dramatic moment. It degrades. Each member begins hedging. Planning quietly shifts from collective scenarios to national contingencies. Joint exercises lose urgency because nobody is sure the promises behind them will hold.

This is where NATO stands now. The formal structures remain intact. The treaty text is unchanged. But the psychological architecture that made collective defense credible is cracking under sustained pressure from its most powerful member.

Democratic senator Mark Warner has stated that Congress will defend NATO against presidential attempts to undermine it. Strong words. But as Daalder observed, NATO Secretary General Mark Rutte’s strategy of flattering Trump, to the point of expressing support for the Iran war despite opposition from virtually all other members, has already failed. Trump acts independently regardless of advice from those attempting to influence him. Congressional declarations of support face the same wall.

The question is no longer whether NATO will change. It is changing. The old alliance — the one where American power underwrote European security in exchange for political solidarity — is functionally finished. What matters now is what replaces it. Europe has the economic weight, the industrial base, and, increasingly, the political will to build a credible defense architecture. What it does not have is time. The Russian threat window opens as early as 2027. The capability gap requires a decade and a trillion dollars to close. That arithmetic is unforgiving.

I believe Europe can build something workable, but not by 2027, and not without accepting risks that no European leader has yet been willing to articulate publicly. That means interim measures — accelerated procurement of off-the-shelf systems, deeper bilateral defense pacts between frontline states, and an honest reckoning with the nuclear question — will matter more than any long-term spending plan. The survival problem is real, the deadline is real, and the margin for diplomatic wishful thinking has run out.

Photo by Paolo Boaretto on Pexels