Four Futures for NATO

NATO’s next summit, which will be held in Ankara on July 7 and 8, has been preceded by widespread debate about the future of the Alliance.

US President Donald Trump, by his account, bid “bye, bye” to allies after Denmark’s refusal to hand over Greenland to the United States. He called NATO a “paper tiger” when allies did not side with the US against Iran, triggering President Emmanuel Macron of France to accuse Trump of “hollowing out” the Alliance. The Pentagon has floated the idea of excluding Spain from NATO and only supporting “model allies” that deliver on defense spending. Furthermore, the Pentagon has announced major troop withdrawals from Germany and Poland, as well as plans to withdraw up to 50 percent of deep-strike assets designated for the continent in times of crisis, which many fear could weaken Europe’s deterrence vis-à-vis Russia.

NATO has survived major challenges before—from the Suez crisis in 1956 to the Iraq War in 2003. The Alliance has repeatedly been declared “dead”—including Macron’s “brain-dead” pronouncement in 2019—but still, it prevails. This time, however, the transatlantic tensions are occurring while NATO is simultaneously undergoing a profound transformation from a US-led to a European-led alliance, as part of a paradigm shift that US Under Secretary of War for Policy Elbridge Colby has termed “NATO 3.0.” The shift has started. But how it will end, and whether it will succeed, will depend on major efforts being undertaken on both sides of the Atlantic.

One and a half years into the second Trump administration, there are broad and intense discussions in Europe about how to organize European security in light of the Russian threat and doubts regarding the US commitment to NATO. Discernible in both the public debate and behind closed doors among politicians, officials, and experts are various possible futures for NATO.

Fundamentally, the discussions are occurring on two dimensions. The first relates to the US security presence in Europe: Will the United States stay or leave? The second is about the nature of burden-shifting from the US to Europe: Will it be modest or brusque? Drawing on these dimensions, below I explore four potential futures of NATO: first, a moderate version of more Europe in NATO; second, a more brutal one; third, a version where NATO narrows to Europe and Canada; and fourth, one where NATO becomes part of the European Union.

Not all versions are equally probable. The Trump administration’s national strategies state clearly that NATO should change, not dissolve, and that the US will keep some level of engagement in the Alliance. In addition, European allies are making the effort to take on greater responsibility within NATO. As a result, in my assessment, a future with more Europe in NATO is most likely, especially if European allies manage to be agile and innovative in filling the void left by the United States. Given the urgency and magnitude of the Russian threat, a stronger Europe in NATO should also be the preferred option. But Trump’s eagerness to shift burdens quickly combined with his unpredictability make the more brutal version of such change the most realistic scenario of the four—a prospect for which Europeans must mentally prepare. Most unlikely is the possible development of the EU into a defense alliance, since so many components for such an outcome to become a reality are still missing.

But the uncertainties regarding where the Alliance is heading are nevertheless great enough to encourage political imagination and, at least, take each possible future into account. Strategic complacency is no longer a viable option as Europeans are facing a new era of major transformation in global affairs.

Toward NATO 3.0

Upon taking office in January 2025, the Trump administration was quick to send signals on NATO to its European allies. On a positive note, the administration conveyed an intention to stay in NATO and create a more “lethal” alliance. More challenging was that the US set out to shift the burden within NATO so that, in principle, Europe took on the “primary responsibility” for conventional forces while the US provided the nuclear deterrent. In other words, the alliance would be European-led with the US in the back seat.

In February 2025, US Secretary of War Pete Hegseth declared that European security no longer was the top priority for the United States, nor was the future of Ukraine, which primarily was a responsibility for Europeans. Moreover, the National Security Strategy from November 2025 does not mention Russia as a threat to the United States. It calls instead for the reestablishment of “strategic stability with Russia”, while declaring that the United States in the future would focus on its own borders, the Western Hemisphere, and the Indo-Pacific. Consequently, the US expected allies to invest heavily in their defense capabilities, spending 5 percent of gross domestic product (GDP) on defense yearly by 2035, so that NATO could serve as a regional tool to stabilize the European continent and allow the United States to move on to more urgent tasks in other parts of the world. The 5 percent pledge on defense spending that allies agreed upon at NATO’s summit in the Hague in June 2025 provided the foundation for the implementation.

Moving from a US-led to a European-led NATO is the most fundamental shift that the Alliance has undergone since its formation in 1949. It is in NATO’s DNA to have the United States at the helm in providing political determination, military leadership, major conventional capabilities on the ground in Europe, and extended nuclear deterrence.

Now, the natural leader of the Alliance has taken a step back while European nations are assuming greater responsibility for supporting Ukraine, leading the joint force commands, and filling capability gaps. A “European pillar of NATO”—a notion that has been discussed since the 1960s—is finally emerging. But at what pace and in which shape?

Future #1: More Europe in NATO—the moderate version

The idea of a European pillar in NATO is by no means new. It was born more than sixty years ago—launched by the Kennedy administration and later picked up by the United Kingdom and its Defense Secretary Denis Healey, who in 1968 initiated a series of “Eurodinners” among NATO defense ministers. The ambition was to shape common European views on NATO matters. The concept was revived in 1985, when the UK argued for the legitimacy of separate European discussions to produce more coherent European contributions to NATO.

As traditionally conceived, a European pillar in NATO is not about replacing American leadership but rather about a more united Europe shouldering a more equal part of the burden within NATO. In other words, it has been about burden-sharing rather than burden-shifting.

During the first Trump administration, this version of a European pillar was frequently discussed as the United States pivoted to the Indo-Pacific and risked overstretching its military across theaters. Consequently, European allies needed to invest more in defense innovation and capabilities to meet the Russian threat and be able to act as first responders if the Americans were locked up elsewhere. After Russia’s full-scale invasion of Ukraine in 2022, NATO’s planning process indicated that Alliance members would need to spend more than an average of 3 percent of GDP on defense by 2030 to realize their minimum capability requirements to counter Russia. NATO has long had the rule that no single ally should provide more than 50 percent of any agreed capability target. But in reality, the United States has contributed 70 percent, 80 percent, or even 90 percent in various categories, especially “strategic enabler” domains. Allied pledges at the Hague summit to invest 5 percent of GDP in defense by 2035, of which 3.5. percent should be on military defense, therefore were not far-fetched but anchored in real assessments.

In the moderate version of a future with more Europe in NATO, the Alliance will remain US-led but European allies will shoulder greater responsibility and deliver up to two-thirds of NATO’s combined operational capacity for collective defense measured in rapidly usable forces, enablers, and other capabilities to execute advance plans across NATO territory. Military leadership roles and structure would be reorganized to reflect the greater share of burden and influence that the capabilities would generate.

Recent transatlantic drift and tensions have not necessarily undermined the chances for this moderate version to become a reality, Although the scenario does not align with the Trump administration’s vision of a more complete transfer of responsibility, it might be where the burden-shifting process lands in the end. Withdrawing troops and capabilities is sometimes not as easy as it seems, which can result in dramatic announcements not always matching implementation on the ground. Furthermore, a new US administration could in three years hamper or reverse some of the decisions taken by the Trump administration and assess the value of American leadership and alliances differently.

Future #2: More Europe in NATO—the brutal version

This is the future where burden-shifting is the main trend but with a real risk of becoming burden-dumping if not managed appropriately. The difference from the moderate version is not the nature of the defense spending and new capabilities that the Europeans need to take on, but rather the pace of those efforts, the lack of coordination across the Atlantic, and the future role of the United States in the Alliance.

The Trump administration is in a hurry to deliver results before the next presidential election in 2028. The Pentagon indicated in December 2025 that the shift to European allies taking the lead in terms of the Alliance’s conventional forces should be accomplished by 2027. This past April, Colby emphasized that “Europe must accelerate its assumption of primary responsibility for the conventional defense of the continent.”

The war against Iran brought further urgency to burden-shifting in depleting US ammunition and missile stocks and erasing enablers such as intelligence, surveillance, and reconnaissance (ISR) platforms. Therefore, discussion between the US and Europe during spring has centered around replacing many American capabilities and troops near-term, that is immediately or within a twelve-to-eighteen-month-timespan. Capabilities such as those involving ISR, command and control, long-range precision strikes, missile defense, air-to-air refueling, and manpower are difficult and expensive to replace at short notice, which means such requests pose a major challenge for Europe.

This future risks being brutal not only because of the pace of change but also because of a disorderly process. Even if the military parts of NATO seek to ensure order in an effort to avoid gaps, political squabbling and outbursts could eventually undermine these institutional mechanisms. For recent examples of how orderly processes have broken down, consider Trump’s sudden decision to withdraw 5,000 troops from Germany, apparently sparked by comments from German Chancellor Friedrich Merz, and to stop a rotational brigade to Poland when parts of the deployment already were on their way.

Each transatlantic crisis undermines trust and makes it harder to restore. The language among European leaders has shifted in the past year. At the Munich Security Conference in February 2026, German Chancellor Friedrich Merz stated that NATO should become a more transactional alliance based on interests, as Europe and the US no longer shared all values. Recently Polish Prime Minister Donald Tusk wrote that “the greatest threat to the transatlantic community [is] not its external enemies, but the ongoing disintegration of our alliance.”

Concerned by Trump’s repeated threats to withdraw from the Alliance, European NATO officials have used informal gatherings to develop contingency plans based on NATO’s existing structures but without US military assets and with Europeans assuming command-and-control roles. EU ambassadors have conducted a tabletop exercise to test how they would implement Article 42.7 of the EU treaty—its mutual-defense clause—in practice.

This brutal future is the most likely scenario in the coming years, as it aligns with the rapid burden-shifting pushed by the Trump administration under its vision of NATO 3.0. Whether it will succeed without chaos will depend both on US capacity to keep the dialogue and coordination with the Europeans going, as well as on sustained major defense investments by the Europeans. European leadership is crucial to avoid burden-shifting turning into burden-dumping.

Future #3: NATO narrows to Europe and Canada

In this future, the United States decides to leave NATO, formally or informally. Dating back to his first term, Trump has repeatedly stated that he may pull the US out of the Alliance—to the extent that the US Congress passed a law in 2023 to prevent the president from doing so without congressional approval, creating a cushion but not a full brake against such an initiative by the president.

A softer, more informal version of this scenario could be the United States acting similarly to France in 1965. France withdrew from NATO’s integrated military command structure, which meant that French units were not placed under NATO command and that France no longer assigned personnel to the staffs of headquarters in the NATO command structure, leaving allies shocked and concerned about the stability of the Alliance. De Gaulle acted out of fear that France would be dragged into the Vietnam War and that the US was too dominant in the Alliance.

France, however, remained an active ally with diplomats at NATO’s political headquarters, as well as in liaison offices at other military headquarters. French armed forces even covertly worked out arrangements for cooperation with NATO in wartime to assure allies that they could count on France in the event of a crisis or war. In the end, the decision turned out to be more of a separation than a divorce—but one that lasted for forty-three years without causing the end of NATO.

Could NATO survive without the United States? Some say no, others yes. Former NATO Secretary General Jens Stoltenberg recently made the case that the Alliance cannot persist without Washington. Former NATO Deputy Supreme Allied Commander for Europe Richard Shirreff, meanwhile, argues that it would be “crazy” to throw away what has been built up over the last seventy-seven years: “What NATO gives, even without America, is a framework, a command structure, a doctrine, a way of doing business.” Maintaining NATO without the US would require its other members to massively increase defense spending starting immediately and to demonstrate firm political determination to follow through on security guarantees. The North Atlantic Treaty would remain a valid foundation for an alliance reorganized to fit the new circumstances.

If the United States were to leave NATO, allies would need to fill the major void of Washington’s extended nuclear deterrence. Europe and Canada would need to increase nuclear deterrence and develop capabilities to handle the escalation ladder from conventional conflict to nuclear warfare independently from the US. This would be difficult, risky, and very costly. Presumably, allies would want to comply with the Treaty on the Non-Proliferation of Nuclear Weapons and not increase the number of nuclear-weapon states, which means that France and the United Kingdom would be at the core of an effort that would include modernizing and expanding their nuclear arsenals, possibly with the financial support of other allies.

As part of this new structure, allies would also have to invest in conventional, ground-based, long-range, precision-strike capabilities. Such conventional capabilities, which would allow allies to hit targets deep inside Russia or another adversary, would be important in managing escalation during a conflict. At the moment, however, Europe does not possess such assets due to American assurances that Washington will provide them as well as concern about not violating  the now-expired Intermediate-Range Nuclear Forces Treaty.

In March, France announced that it will increase its nuclear-weapons arsenal and extend its nuclear deterrence to cover other European countries through, as one assessment by the International Institute for Strategic Studies put it, “consultation, signalling and potentially dispersing aerial nuclear assets in an ‘archipelago of forces.’” Eight other European countries—the UK, Germany, Poland, the Netherlands, Belgium, Greece, Sweden, and Finland—agreed to participate with France in a new “advanced deterrence” strategy. However, this arrangement will not resemble the American nuclear umbrella and must be complemented by the development of a more European way of warfighting.

Ultimately, for European extended deterrence to work, Russia would have to be convinced that France and the UK would risk their homelands and strike Moscow if an ally were attacked. And equally, Europeans would need to believe that they can defend themselves and be willing to do so. Without resolve, deterrence will not be credible even if the capabilities come into place.

Is a future in which the United States leaves NATO likely? It cannot be excluded as a possibility, but Trump’s repeated threats to do so could also be the products of his frustration with European allies or bargaining tactics with them rather than reflecting a genuine wish to pull the US out of the Alliance. None of the Trump administration’s current documents guiding US foreign and security policy or military deployment in Europe hint at the possibility of the United States withdrawing from NATO. Changing NATO, yes. Leaving NATO, no.

NATO provides many advantages to the United States, including protecting the US homeland from Russian nuclear weapons and enabling the US to project power worldwide by using bases on the continent. If Europe and Canada continue to invest in defense and take on more responsibility within the Alliance, the transactional benefits across the Atlantic will probably prevail. But conversely, a failure by Europe and Canada to do these things could cause the end of American engagement.

Future #4: NATO becomes part of the European Union

In this future, the European Union becomes the alliance around which the defense of Europe is organized and NATO is dismantled. Such a development would be triggered by an American withdrawal from NATO—either formal or informal—and European leaders calculating, in contrast to the previous scenario, that they do not consider NATO worth preserving. Such a decision could stem from a strong desire to develop the EU as a global actor. Article 5, the mutual-defense clause of the North Atlantic Treaty, would be replaced by Article 42.7 of the Lisbon Treaty as the glue for collective defense.

In this scenario, allies that are not members of the EU—such as the UK, Canada, Norway, Iceland, and Turkey—could be invited to enter into the new defense structure through bilateral defense agreements with the EU that include mutual security guarantees. Ukraine could also be part of such an arrangement.

This future would require a great deal of political determination and unity. The EU’s recent experience with Hungary, which constantly blocked actions related to foreign and security policy, clearly illustrate the vulnerability of the bloc’s decision-making process. By construct, the EU lacks a leading nation equivalent to the United States in NATO. Introducing majority voting in the EU could partially address some of the difficulties, but it would hardly be applicable in the most severe scenarios anyway. The EU would have to build a strategic culture of resolve that is not yet in its DNA.

Despite recent attempts to ramp up defense spending and collaboration, the EU lacks most of the components needed for it to be a functioning military alliance. Deliberately, the EU has avoided duplicating NATO when it comes to, for instance, command, control and communication procedures such as the defense-planning process and standards for interoperability. That means these components would have to be built from scratch—a costly and time-consuming endeavor.

The challenge of a nuclear deterrent would be similar to the one in the previous scenario, with France playing a key role, possibly supported by an associated UK. But in this future there is also the option of developing a common European deterrent in which the authority to launch nuclear weapons would move to a European entity rather than staying in the hands of a member state. Such a solution, with buy-in from all member states, could make deterrence more credible and be easier to sustain financially. However, there would also be serious hurdles to a Eurodeterrent, not least the unwillingness of European nuclear states to give up their current authority.

Despite frequent calls over the past decade—mostly from France—for greater European independence, the EU has never seriously challenged NATO as the military alliance for Europe. All defense initiatives within the EU have been more or less complementary to NATO. To even consider centering European defense efforts around an institution that does not include the largest military players—the US, the UK, and Turkey—has not made much sense to most European states.

But with Germany’s efforts to build the largest conventional army in Europe by 2029, and Poland investing heavily in defense as well, this calculus is starting to change. Polls show record-high public support across Europe for a common security and defense policy in the EU. European Commission President Ursula von den Leyen has claimed that the European Union is building a “military powerhouse” and wants a new security strategy to guide the EU in a new geopolitical setting. When Trump threatened to take Greenland in January 2026, French President Macron claimed that Europeans have a “specific responsibility” for the island and sent troops to support Denmark’s efforts to uphold territorial integrity.

But even in the case of Greenland, there was no consensus in Brussels about whether Article 42.7 was applicable—with apparent disagreement between von der Leyen and Defense Commissioner Andrius Kubilius. It was a reminder that turning the EU into a military alliance is still a very distant project. Given the magnitude of the Russian threat, time is not on the EU’s side.

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The four futures for NATO sketched above reflect how poised for transformation the transatlantic relationship is. Perceptions differ among allies, from those who believe that in practice, the transatlantic community is only under-going a bump in the road, to those who see an independent Europe as the only viable option ahead.

Even though the most likely future is that NATO prevails with the United States remaining in the Alliance and its European allies assuming more responsibility within it, it is clear that the road going forward will be bumpy as the Alliance undergoes profound changes.

The uncertainties regarding its future direction are considerable enough to require open minds and open discussions across the Atlantic among political and military leadership, experts, and the broader public.

Given the severe threat that Russia poses to Europe, Europeans deserve nothing less from its political leadership than serious steps toward greater European responsibility on defense while keeping the United States engaged. That work has now started. At the Ankara summit and beyond, increased defense investments must be paired with agile and creative leadership to increase readiness, fill capability gaps, and adapt operational plans to a European way of fighting.

Anna Wieslander, PhD, is chair of the board of the Institute for Security and Development Policy. She serves as director for Northern Europe at the Atlantic Council and head of its Northern Europe Office in Stockholm. During spring she has been a visiting scholar at the Centre for Geopolitics at the University of Cambridge where she gave a presentation on the “The Four Futures of NATO”. You can watch the event here.