At a high-level meeting earlier this year, top foreign ministry officials from several European countries were asked a blunt question: who among them still genuinely believed that the United States would come to their defense if they were subjected to a military attack?

Not a single hand went up.

The silent room provided a stark, undeniable indication of the extent to which European governments have concluded that the United States—long the bedrock of European and NATO security—can no longer be relied upon as a steadfast ally. Over the past 18 months, diplomatic conversations in Brussels and other key NATO capitals have largely revolved around how to boost the continent’s conventional defense capabilities to make up for Washington’s steady retrenchment. However, a much quieter and significantly more urgent discussion is simultaneously taking place behind closed doors, focused squarely on the ultimate deterrent: the future and credibility of the U.S. nuclear guarantee.

More than half a century ago, what the French strategist Raymond Aron termed the "Great Debate" erupted between European countries and the United States over how to preserve European nuclear deterrence in the face of the Soviet Union’s expanding nuclear capabilities. Back then, European leaders deeply feared that Washington’s growing emphasis on the conventional defense of the continent reflected an increasing reluctance to protect Europe with nuclear weapons, particularly as Moscow successfully developed intercontinental missiles capable of reaching the U.S. homeland. The central, haunting question of the era was simple yet profound: Would the United States truly be willing to risk Boston to defend Berlin?

That historic debate was ultimately resolved through a delicate new grand bargain. In return for a binding commitment from European countries to completely forgo developing their own independent nuclear weapons, the United States agreed to invite much greater European participation in strategic nuclear decision-making. That essential transatlantic bargain successfully stuck for 60 years, helping secure both the United States and Europe while robustly preventing widespread nuclear proliferation across the globe.

Now, however, that foundational bargain has decisively come undone. Washington has signaled that it desires a fundamentally new division of labor: European nations must take on primary responsibility for their own conventional defense, while the United States supposedly continues to ensure their nuclear defense. Yet, regional analysts and officials argue that this shifting arrangement hardly addresses the underlying crisis.

"If you don’t believe in the United States’ Article 5 commitment," one of the senior officials attending the recent meeting noted, "then extended deterrence is effectively dead."

Already, alternative and radical options are being seriously considered across the continent. In several European capitals, officials are quietly raising the unsettling possibility of acquiring their own national nuclear arsenals. Meanwhile, France has stepped forward with offers to adapt its independent nuclear policy in an effort to help defend its vulnerable European allies.

Each of these prospective options possesses its own internal strategic logic. However, none of them adequately addresses the monumental challenge of ensuring robust European security without risking a dangerous cascade of further global proliferation. A vastly better approach would be a fourth alternative: a renewed U.S.-European nuclear bargain, this time anchored by a real European core. Led closely by France and the United Kingdom, NATO’s European members must take on a vastly larger and more active role in their own nuclear deterrence while simultaneously working to restore the vital transatlantic defense link that has served as the foundational pillar of U.S. and European security for decades.

FOUNDATION OF PEACE

The Soviet Union’s 1957 launch of the Sputnik satellite posed a profound and immediate dilemma for the fledgling NATO alliance. Until that milestone moment, the alliance had comfortably counted on U.S. nuclear weapons deployed directly across Europe to deter a potential attack by a much larger Soviet conventional force. But once Moscow dramatically demonstrated its capability to launch intercontinental rockets, Europeans grew deeply fearful that the United States would no longer be willing to risk absolute devastation to prevent a Soviet invasion of Europe.

These rising concerns sparked a fierce, multi-year debate within NATO regarding how the continent could independently or collectively ensure its nuclear defense. Some factions, led firmly by France, were thoroughly convinced that European countries desperately needed to acquire their own sovereign nuclear weapons. Others sought less costly, more cooperative ways to restore a degree of direct control over nuclear deterrence. One notable American idea that gained substantial traction at the time was the creation of a multilateral force—envisioned as a fleet of shared vessels carrying roughly 200 ballistic missiles. Such a multilaterally operated and funded force was designed to give Europeans a tangible sense of ownership and operational control over the potential use of nuclear weapons, while still preserving the U.S. president’s ultimate constitutional authority over their launch.

The debate exposed a fundamental, structural problem inherent in extending U.S. nuclear deterrence to distant allies, especially when an entire ocean separates those allies from Washington. An adversary might theoretically be deterred from attacking an American ally by even the slimmest possibility of a devastating U.S. nuclear retaliation, given that the catastrophic consequences of a miscalculation would be entirely unacceptable. But that exact same tiny, five-percent probability would offer precious little comfort to the ally on the ground, who desperately needed to believe that Washington would actually risk national destruction on their behalf. Denis Healey, who served as the United Kingdom’s defense secretary throughout much of the 1960s, famously postulated what became known as the Healey theorem: "It takes only a five percent credibility of American retaliation to deter an attack, but it takes a 95 percent credibility to reassure the allies."

The historic debate was ultimately resolved through a durable bargain. Washington’s European allies agreed to formally forgo their sovereign right to acquire nuclear weapons in return for a significantly greater say in U.S. nuclear weapons policy and military strategy. Although the expensive and complex idea of a multilateral fleet was ultimately abandoned, the creation of the NATO Nuclear Planning Group provided a crucial vehicle for Europeans to provide direct input into U.S. nuclear planning. It also gave Washington a practical mechanism to demonstrate that European security interests were deeply integral to its overarching nuclear strategy and force posture. Reassured by this arrangement, European countries—with the notable exceptions of France and the United Kingdom—agreed to codify their strictly nonnuclear status in the landmark 1968 Nuclear Nonproliferation Treaty.

Many European countries retained ground- and air-based systems capable of delivering U.S. nuclear weapons deployed on their sovereign territory. Today, about half a dozen European countries still deploy dual-capable aircraft capable of carrying U.S. B-61 nuclear gravity bombs. These intricate nuclear consulting and sharing arrangements proved far more crucial to reassuring jittery allies than the hard-power measures, such as counterforce targeting, low-yield tactical weapons, and greater precision, that U.S. military strategists typically believed were essential. While hard-power metrics focused heavily on resolving the five-percent deterrence problem, consultative mechanisms directly addressed the 95-percent questions of political reassurance.

France stood alone as the only major nation to flatly reject this comprehensive nuclear bargain. Although the United Kingdom had achieved independent nuclear power status in the 1950s, it chose to commit all its strategic weapons to NATO and actively participated in both the Nuclear Planning Group and dual-capable aircraft missions. Under the leadership of President Charles de Gaulle, however, France came to firmly believe that it could never truly count on another foreign country for its ultimate nuclear security. Paris embarked on an independent national nuclear program, stubbornly refused to participate in the Nuclear Planning Group or dual-capable aircraft missions, and, in 1966, formally withdrew from NATO’s integrated military command structure. Despite the French defection, the broader global bargain successfully laid the bedrock foundation for what became a remarkably resilient and successful deterrence, reassurance, and nonproliferation regime.

DEAL BREAKER

Unlike the intense debates of the 1960s, today’s renewed nuclear crisis has not been prompted by a gradual shift in the global balance of power. Instead, it has been abruptly precipitated by a unilateral and profound change in the United States’ fundamental attitude toward Europe. In Trump’s second term, the United States has effectively rejected the two core principles that have long governed NATO’s collective defense commitments: the shared understanding of mutual threats to NATO members and the foundational premise that members’ security is completely indivisible.

European members of NATO can no longer safely assume that the U.S. commitment to their security—derived from the historic idea, born out of the ashes of two devastating world wars, that American security is inextricably linked to the stability of Europe—remains ironclad. Instead, as Pentagon policy chief Elbridge Colby has repeatedly and publicly noted, "under President Trump’s leadership, the simple fact is that countries can no longer take America for granted."

European nations, however, point out that they have never taken America for granted. They firmly assumed that Washington shared their core belief in the indivisibility of transatlantic security—a principle they dramatically proved when NATO invoked Article 5’s collective-defense obligation for the first and only time in history, rallying immediately in response to the September 11, 2001, terrorist attacks on the United States.

The current American president and other senior administration officials have made it abundantly clear that the United States’ security commitment to Europe is no longer anchored in a shared understanding of common threats. Rather, it is increasingly based on secondary, transactional considerations, such as European countries’ specific levels of defense spending and their explicit diplomatic support for broader U.S. foreign policy objectives. In August, the Pentagon transmitted a lengthy, detailed questionnaire to all 31 NATO allies, heavily emphasizing the strict conditionality of Washington’s security commitment. The document bluntly asked allies to profess direct loyalty to the administration’s foreign policy, commit heavily to procuring advanced defense equipment exclusively from U.S. firms, and prioritize funding the restoration of the domestic U.S. industrial base by actively opposing any local "buy European" defense initiatives.

While some European NATO leaders still publicly deny that anything fundamental has shifted in the transatlantic relationship, most privately acknowledge they have reached the exact same sobering conclusion as senior European political officials: the United States can no longer be counted upon to automatically come to Europe’s defense. If that grim assessment applies to conventional warfare, regional leaders concede it is doubly true regarding the ultimate U.S. nuclear guarantee.

This stark reality leaves Europe confronting terrifying questions it has never seriously had to ask before. What if Russia were to launch a conventional or hybrid attack on NATO territory and Washington abruptly informed Europe that it was entirely on its own? How could nonnuclear European allies possibly stand up to a hostile, nuclear-armed Russia? What if Moscow chose to use implicit or explicit nuclear coercion to force European capitals to completely abandon their military and financial support for Ukraine?

None of these threatening scenarios are far-fetched or purely hypothetical. Russia has issued thinly veiled nuclear threats against Europe repeatedly since 2022, most recently in September, shortly after NATO conducted large-scale air exercises above northeastern Poland, uncomfortably close to the heavily militarized Kaliningrad enclave.

FOOL’S BARGAINS

As the security gap widens due to shifting U.S. policies, three distinct strategic options have begun to emerge across Western capitals to fill the impending void.

Washington favors attempting to reestablish a modified nuclear bargain based on a brand-new distribution of responsibilities, frequently referred to within American defense circles as NATO 3.0. "We will continue to provide the U.S. extended nuclear deterrent," Colby told allied defense ministers earlier this year, "with Europe taking the lead for its conventional defense." The United States has even floated the possibility of expanding its existing nuclear umbrella by extending nuclear sharing arrangements to newer frontline countries, such as Poland, and developing a sophisticated next-generation nuclear gravity bomb for potential future deployment on European soil.

Yet, this American-favored option fundamentally ignores the core problem. The current U.S. administration has done virtually nothing to convince its anxious allies that Washington remains committed to the alliance beyond mere verbal assurances. No additional military hardware or weapons deployments can possibly compensate for the central, alarming implication that U.S. security commitments to European partners are now entirely conditional upon shifting political loyalty.

A second, more drastic option would involve ending the transatlantic nuclear bargain altogether. Under this scenario, European countries would abandon reliance on external guarantees and move aggressively to acquire their own sovereign nuclear arsenals. The clearest political articulation of this concept emerged in March 2025, when Polish Prime Minister Donald Tusk bluntly told his nation’s parliament that "we would be safer if we had our own nuclear arsenal, that is beyond doubt." A year later, he informed his cabinet that Poland would actively "strive to prepare . . . for the most autonomous actions possible" regarding national nuclear security.

Poland is far from alone in weighing this path. In Sweden, various political figures have publicly invoked the country’s secretive, abandoned nuclear weapons program from the 1960s to signal a renewed interest in pursuing a national capability. Even in Germany, where defense debates have historically been strictly constrained by its twentieth-century history, a senior Bundeswehr general argued publicly earlier this year that Germany "needs its own tactical nuclear weapons"—an assertion that would have been completely unthinkable just a few years ago. Similar proliferation conversations are simultaneously echoing across Asia, particularly in South Korea, raising the grim prospect of a dangerous global cascade of allied nuclear proliferation.

In theory, if a growing number of European countries acquired independent nuclear weapons, it could theoretically resolve the extended deterrence dilemma. In practice, however, it is entirely unworkable. It would take many years and immense economic resources for Poland, Sweden, or Germany to successfully develop credible, independent nuclear deterrents. Furthermore, widespread European nuclearization would decisively shatter the Nonproliferation Treaty architecture that the original 1960s U.S.-European nuclear bargain was deliberately built to protect. It could easily trigger a localized arms race, rendering Europe significantly less secure rather than more protected. A strategy originally designed to bolster deterrence would ultimately end up weakening the very alliance structure it aimed to safeguard.

As an alternative to these flawed approaches, France has spearheaded a third diplomatic and military strategy aimed at replacing, or at least substantially augmenting, the fading U.S. umbrella. French President Emmanuel Macron formally proposed this solution during a major policy speech in March 2026, announcing a "forward deterrence" initiative. This framework aims to include European allies in joint nuclear training exercises, temporarily forward-deploy French nuclear-capable aircraft on allied soil, and host extensive, high-level nuclear discussions with participating partner countries. So far, ten European countries have officially joined the initiative by establishing bilateral nuclear steering groups to discuss French nuclear strategy and explore how its evolution could enhance regional security.

Macron’s proposal represents a major intellectual and strategic evolution in French defense thinking by explicitly extending France’s vital national interests to encompass the security of its European partners. Paris’s newfound willingness to engage its European neighbors in direct, transparent talks about nuclear issues has been largely welcomed across the continent.

However, there remain significant structural drawbacks to the French initiative. In his formal announcement, Macron reiterated the long-standing "four nos" that strictly underpin French defense doctrine: no joint political decisions on nuclear weapons use, no joint nuclear planning, no shared definition of French vital interests, and no official nuclear guarantee "in the strict sense of the term." Moreover, the framework’s heavy reliance on bilateral discussions rather than multilateral structures directly weakens the core principle that European defense ought to be a collective, unified NATO effort.

Crucially, France’s distinct nuclear doctrine—which traditionally allows for a limited warning strike followed by a devastating, total response if the initial warning fails to deter the aggressor—provides Paris with fewer flexible options for managing conflict escalation compared to NATO’s more graduated strategic approach. This narrower range of options could ultimately render French nuclear threats far less credible in a high-stakes conflict over a distant ally’s security. Ultimately, while the French proposal adds a measurable degree of reassurance and deterrence, it falls short of entirely overcoming the massive security void created by shifting U.S. policies.

MUTUALLY ASSURED PROTECTION

None of the three options currently being debated fully resolve Europe’s deepening extended nuclear deterrence dilemma. Yet, valuable elements of all three point the way toward a viable, comprehensive solution.

NATO urgently needs to bolster both the European and the U.S. legs of its collective nuclear deterrence posture, formally bring France into its internal nuclear consultation and planning structures, and expand existing nuclear sharing arrangements to incorporate additional member states. These monumental tasks will require NATO members, particularly the alliance’s three nuclear-armed powers, to make significant, uncomfortable adjustments to their long-held beliefs and established policies. The only alternative is not the status quo—which is already completely unsustainable given the severity of the Russian threat and radical shifts in U.S. policy—but a rapid, destabilizing wave of nuclear proliferation.

To avert this crisis, NATO countries will ultimately need to agree to three major adjustments in their overall nuclear posture: altering the sheer number and types of weapons deployed, transforming how nuclear and nonnuclear NATO members consult with one another, and updating the alliance’s overarching doctrine for the potential use of nuclear weapons.

First, NATO’s existing nuclear powers urgently need to modernize their strategic and tactical forces. The United States should replace the aging B-61 gravity bomb, which will become increasingly difficult to deploy effectively against heavily defended modern air-defense targets, with a modern stand-off cruise missile capable of striking deep into Russian territory from the relative safety of NATO airspace. Such modernization is already long overdue.

In addition, European nations should collectively agree to develop a long-range missile system that could be outfitted with a nuclear warhead jointly developed by France and the United Kingdom. This new missile system should be fully financed by European nations and rendered deployable on advanced aircraft owned and operated by nonnuclear allies. Finally, these modernized U.S. and European nuclear capabilities need to be forward-based across a much wider range of NATO countries, thereby substantially expanding European participation in the frontline nuclear deterrent mission.

While hardware modifications are necessary to restore the physical credibility of Europe’s nuclear deterrence, the "software" of political consultation must remain at the very core of the effort, exactly as it was during the 1960s. Back then, France stubbornly refused to join the NATO consensus and withdrew entirely from the integrated military command structure. Even when Paris finally returned to the military command in 2009, its national nuclear deterrent remained strictly independent, and it chose not to join the Nuclear Planning Group.

That persistent insistence on absolute national independence is precisely what led Paris to pursue bilateral nuclear arrangements this year. However, these parallel bilateral discussions not only create confusion and diplomatic distrust regarding France’s true long-term intentions among its dialogue partners; they also fail to foster the deep political cohesion that could naturally arise from a collective European nuclear deterrence dialogue.

Simply put, Paris needs to formally join the NATO Nuclear Planning Group. Doing so would not automatically place its sovereign nuclear capabilities under NATO command and control, nor would it strip France of its ultimate independence. But it would give European partners a much clearer understanding of French strategic thinking while affording Paris far deeper knowledge of Europe’s critical requirements for deterrence and reassurance.

European members of the Nuclear Planning Group could readily agree to meet regularly without the United States present to discuss how to best integrate the new European nuclear missile forces into NATO’s broader nuclear strategy. For many years, countries hosting U.S. nuclear forces have met separately from other NATO members within specialized NPG formats; a similar, European-only caucus would build solidly on that established historical precedent.

The third necessary adjustment must be strictly doctrinal. One critical element of NATO’s nuclear doctrine cannot and will not change: the ultimate political decision to authorize the use of nuclear weapons will always reside exclusively with the recognized nuclear powers—France, the United Kingdom, and the United States. These monumental decisions can never be delegated to committees or non-state actors, and national nuclear deterrents will continue to be guided strictly by national doctrine rather than formal NATO control.

If France wishes to maintain its traditional one-warning-shot escalatory doctrine, it remains entirely free to do so, even after joining the Nuclear Planning Group. However, Paris would then be required to clearly explain how this specific doctrine would effectively reassure anxious allies and enhance collective deterrence.

At the same time, France’s active participation in the Nuclear Planning Group, combined with the addition of a new European-backed nuclear missile force, would dramatically expand Europe’s direct influence over the ongoing development of NATO’s nuclear strategy. Most importantly, it would directly confront Moscow with the undeniable reality that the strategic decision to use nuclear weapons in defense of Europe no longer rests entirely in Washington’s hands alone.

These are profound posture adjustments that will demand significant, courageous changes in policy and perspective across the alliance. Washington will ultimately have to accept that the deployment of additional European nuclear forces means it can no longer unilaterally dictate NATO’s nuclear policy and strategy—including, crucially, the final decision regarding weapons use.

Paris, meanwhile, must accept deeper operational and consultative integration into the broader NATO architecture. London will need to extend its existing bilateral nuclear cooperation with the United States to include France, potentially develop a secondary nuclear delivery system alongside its submarine force, and find the necessary financial resources to design and build a brand-new warhead in close collaboration with French engineers.

Meanwhile, nonnuclear European countries will have to agree to finance the costly development and procurement of these new missile systems and potentially supporting aircraft, though they will naturally refrain from acquiring nuclear warheads themselves to maintain strict compliance with international treaties. These nonnuclear allies must also collectively finance vital security, communications, and logistical upgrades to enable the expanded deployment of dual-capable aircraft across the continent.

Most importantly of all, these nonnuclear European allies would need to publicly and collectively reiterate their firm commitment to permanently forgoing national nuclear weapons of their own, powerfully reaffirming the essential bargain that was cemented six decades ago.

None of these sweeping transformations will happen quickly or easily. They will require London, Paris, and Washington to voluntarily relinquish a tightly guarded element of control over their respective nuclear arsenals that each has jealously protected for more than 60 years.

Yet, the alternative paths are far worse. The security of Europe and the United States is, in absolute terms, indivisible, no matter what transient political shifts may dictate policy in Washington. If Europe were ultimately left entirely to fend for itself and nuclear weapons began spreading unchecked from capital to capital, American citizens would find themselves significantly less safe, not more.

At the same time, U.S. strategic retrenchment is a palpable reality, and no amount of empty diplomatic reassurance from Washington will restore the credibility of a nuclear guarantee that Europeans have grown to profoundly doubt. With the United States pulling back from its traditional global commitments, forging a brand-new bargain in which Europe successfully carries more of the nuclear burden while retaining a decisive voice in the choice to use these weapons remains the only viable path to ensuring long-term transatlantic security.