When it comes to securing Ukraine’s future, to paraphrase Winston Churchill, armed neutrality is the worst option for the United States and NATO, except for all the others.
As the Russo-Ukrainian war approaches its third anniversary, the conflict may be nearing a turning point. Ukraine’s military is dangerously exhausted, facing worsening manpower shortages and the prospect of diminishing Western aid. Russia, despite steady gains, hasn’t scored a decisive breakthrough and is suffering high losses amid tightening economic constraints. Meanwhile, President Donald Trump has promised to end the war and has already held discussions with Russian President Vladimir Putin to get negotiations started.
Whenever peace talks begin, they will be difficult and complex. While questions about territory will most likely be settled on the battlefield, arrangements for Ukraine’s long-term security will be a stubborn sticking point. Several alternatives have been proposed, including NATO membership with its Article 5 guarantee, a bi- or multilateral security guarantee from the United States or a group of European states, or “armed neutrality” — which would leave Ukraine with no security guarantee but with substantial military assistance. While Ukrainian President Volodymyr Zelensky argues NATO membership is the only way to ensure a lasting peace, many current alliance members, including the United States, are opposed, unwilling to take on the additional security burden.
The perceived safety offered by NATO membership is a dangerous illusion for Ukraine, however. Although it is described as “ironclad,” the alliance’s Article 5 commitment is not quite the guarantee Kyiv might hope for. Article 5 does not require members to respond with military force against an aggressor, and its deliberately vague wording gives allies the freedom to decide how and when to react. As a result, past Western refusal to send military forces to defend Ukraine in 2014 and 2022 would weaken the credibility of any formal security guarantee offered to Kyiv by NATO countries. Words alone would not prevent a deterrence failure, and an American tripwire force — which might address this risk — has already been ruled out by successive presidential administrations. Worse, by extending an unreliable commitment to Ukraine, NATO would also undermine the credibility of Article 5 guarantees to existing members.
Of proposed alternatives, only armed neutrality avoids these consequences while offering the most promising chance for long-term peace. Ukraine’s armed neutrality would, however, come with responsibilities for NATO members, especially in Europe, to help Kyiv build its arsenal and fortify the continent’s own defenses.
Dubious Guarantees
Since Trump’s November 2024 presidential election win, Ukraine and its supporters have feared that his promise to bring the war to a quick end would halt U.S. military aid and push Kyiv into an unfavorable settlement. An imposed peace deal that leaves Ukraine with no support would not serve America’s or Trump’s interests, however. Most importantly, past research suggests that forced war settlements rarely last. Not only would Kyiv have incentives to undermine a deal that it felt pressured to accept, especially one it saw as a surrender, but Russia might be emboldened to launch a third invasion into a defenseless Ukraine, hoping to seize more territory or extract more political wins from the West. Renewed war would once again put Moscow and NATO at risk of direct conflict, while Russian geographic gains would further erode Ukraine’s sovereign territory and allow Russia to pose new threats to Ukraine’s neighbors. For Trump himself, a resumption of hostilities would mark a foreign policy failure and challenge his “peace through strength” narrative — and, if Kyiv fell, he might be faulted for “losing Ukraine.”
Trump’s early and proactive commitment to negotiations suggests that he may have at least one goal in common with Zelensky: reaching an enduring settlement to the war. Efforts to achieve a lasting peace between Ukraine and Russia face a commitment problem, however. A history of distrust and broken agreements mean that neither side believes that the other will adhere to a deal. At first blush, security guarantees seem to address this problem by offering one or both sides an assurance that renewed aggression will be met with consequences, including external military support and retaliation.
Ukraine’s preferred security guarantee is a rapid accession to NATO. Recalling the toothless assurances contained in the 1994 Budapest Memorandum, Ukrainian leaders have repeatedly expressed the view that the more binding insurance of Article 5 (and the implied protection of the U.S. nuclear umbrella) would be the best way to provide Ukraine the security it needs. In December 2024, for instance, Zelensky told European leaders that “An invitation for Ukraine to join NATO is a necessary thing for our survival.”
However, Ukraine’s membership in NATO is essentially a non-starter as a condition for peace with Russia and as a credible commitment by the United States and its European allies. Though there remain disagreements about Putin’s objectives for his 2022 invasion, the repeated pledge to bring Ukraine into NATO was a key contributing cause of the war, and Moscow would almost certainly prefer to continue fighting than allow it to join the alliance. Moreover, NATO has already demonstrated twice that it is unwilling to come to Ukraine’s defense when the latter has been invaded, assessing the risks to be higher than the interests at stake. This would undermine the credibility of a future NATO guarantee to Ukraine. After all, simply extending NATO membership on paper to Ukraine would not change allied cost-benefit calculations. As importantly, an uncredible NATO commitment to Ukraine would deal a devastating blow to the alliance’s existing guarantees, especially those on the eastern front, which would seem even more uncertain. While Secretary of Defense Pete Hegseth seemed to rule out NATO membership for Ukraine in recent remarks to other European leaders, he later walked that back, saying instead that “everything is on the table.”
A bilateral U.S. security guarantee for Ukraine would be similarly unacceptable to Moscow and unworkable for the trans-Atlantic alliance, whether it took the form of a more binding mutual defense agreement like the U.S.-Japanese treaty relationship or something more flexible like the 1975 U.S. memorandum of agreement with Israel. The United States has long been clear that Ukraine’s alignment is not a national security imperative and that the balance of resolve would always be in Moscow’s favor in a showdown over the country. Speaking in 2016, President Barack Obama acknowledged the limited U.S. stakes in Ukraine, arguing that “we have to be very clear about what our core interests are and what we are willing to go to war for.” Nothing Trump or President Joe Biden have said or done has wavered from this basic assessment. Ukraine’s non-NATO status is thus the consequence, not the cause, of America’s lack of vital interest in guaranteeing its defense. In the words of former President Richard Nixon, “Our interests must shape our commitments, rather than the other way around.”
Given its explicit refusal to defend Ukraine in the past, any U.S. promise to do so in the future would face questions about its reliability, especially without an accompanying deployment of U.S. military forces, which Trump and his advisors have already ruled out. For his part, a U.S. miliary presence in Ukraine would also be unacceptable to Putin, who has made clear that he views the presence of American forces and military infrastructure in eastern Europe as the main threat posed by NATO expansion.
European guarantees to Ukraine might seem more credible on the surface. After all, Europe has a common interest in balancing Russia with an independent Ukraine as a buffer. If Ukraine were to become a member of the European Union, for example, it would fall under the Lisbon Treaty’s mutual defense provision. Although the provision is modeled on NATO’s Article 5, it has not been sanctified in the same way and remains more ambiguous in nature. Still, a European security commitment would bring its own limitations and complications for NATO.
Technically, European guarantees would not implicate Article 5, as European states would be acting outside the umbrella of the alliance. But in practice, it would prove difficult, if not impossible, to separate European guarantees to Ukraine from de facto NATO protection, especially if European forces were attacked. To prevent entanglement, the firewall between NATO and any European guarantor coalition would have to be extensive. Such carveouts would inevitably and significantly weaken the alliance by formally conditioning commitments that are supposed to be grounded in a substantive strategic imperative for common defense. This would present an insoluble dilemma: If Ukraine and Russia got into a future war and only some European states came to Kyiv’s defense, either the rest of NATO would have to stand aside as their allies are attacked — undermining the alliance beyond repair — or the formal limits placed on Article 5 would fail, leaving the alliance splintered between those dragged into war and those seen as reneging on their commitments.
Armed Neutrality and Its Benefits
The final option, “armed neutrality,” would come with no foreign security guarantees, but it would not leave Ukraine defenseless. Ukraine would give up its bid for NATO and likely also E.U. membership permanently — or at least for an extended period — and the country would be turned into a bristling porcupine that would be difficult and costly for Russia to invade in the future, with impenetrable barriers and anti-tank mines on its de facto borders, strong air defense capabilities, and abundant munitions. NATO would likely never agree to commit in writing to limits on Ukraine’s alliance membership, as the alliance has long insisted that no third country has a veto over NATO membership decisions. Moscow, meanwhile, would also be unlikely to accept informal assurances from NATO given what it sees as a history of broken promises from the West. Ukraine could therefore agree to formally withdraw or indefinitely pause its NATO and E.U. membership bids as part of a larger political settlement, or could commit to non-aligned, neutral status in its constitution, as Kyiv has done in the past.
As a neutral state, Ukraine would still need significant military support from the United States and Europe to build an arsenal capable of deterring Russia and defending its territory. The United States and NATO allies have limited stocks remaining and constrained defense production capacity today but, since Russia too will need time to rebuild before it can consider a renewed attack, they will have five to 10 years to help Ukraine build a credible deterrent.
Early tranches of aid would focus on defensive capabilities limited by what the United States can still provide at scale given global commitments: anti-tank mines, concrete for constructing barriers like dragon’s teeth and trenches, short-range artillery, and some types of ammunition. Though Ukraine has made some defensive efforts, there is still much it can do to make areas near its long borders with Russia inhospitable to invaders. Ukraine might also use military assistance dollars to help recruit and train a large fighting force and capable reserve. Continued investment in Ukraine’s drone development can supercharge its production of uncrewed systems, which can be used for surveillance or to harass adversary forces in the event of an attack. Later tranches of assistance might include command-and-control systems, some longer-range munitions, and armored vehicles. Initially, the United States would lead Ukraine’s rearming, but as defense production in Europe increases, it should assume primary responsibility for arming Ukraine. Ukraine’s history as a defense manufacturing powerhouse should also be leveraged by investing heavily in its indigenous weapons production. Finally, to procure sufficient air defense capabilities at all ranges, Ukraine will need to exploit many procurement pathways, including co-production arrangements between foreign and Ukrainian firms.
Critics have deemed armed neutrality “doomed to fail,” but a careful analysis suggests it is Ukraine’s least risky option. In this scenario, Kyiv would be responsible for its own security. It would have to invest in rebuilding its defense-industrial base and strengthening and modernizing its combat capabilities over the long term, with help from the United States and Europe. But along with the burdens of independence, it would also receive the benefits of self-sufficiency.
Indeed, history offers frequent reminders that the only truly “ironclad” defense is the one a country provides itself. It is — as Kenneth Waltz famously claimed — ultimately a “self-help” world. In many ways, Ukraine’s situation parallels that of Finland after World War II. Having successfully halted the Soviets in the Winter and Continuation Wars, Finland’s relative weakness nonetheless forced it to effectively accept a Soviet veto on its foreign policy, in exchange for preserving its political independence and a formidable fighting force. While “Finlandization” has been regarded by some as a synonym for capitulation and loss of sovereignty, armed neutrality in fact preserved Finland’s domestic autonomy, allowing it to enjoy political liberties and a high standard of living on par with its western European neighbors.
According to Tomas Ries’ study of Finnish defense, Finland’s postwar independence was sustained by three factors: determination to fight, a realistic balance of deterrence with “reassurance,” and the larger challenge for the Soviets posed by NATO. Armed neutrality would leave Ukraine well-positioned on these three dimensions. First, Ukrainians have shown the will and ability to defend their territory against Russian aggression despite their numerical and material disadvantage. Ukraine’s military balance with Russia is also more favorable than that between Finland and the Soviets. Second, by renouncing its NATO aspirations but building its military capabilities, Kyiv could assuage Russian concerns about Ukraine acting as a Western “springboard” while maintaining formidable independent combat power. Armed neutrality would thus balance reassurance with credible deterrence, while reducing the benefits and increasing the costs of renewed Russian aggression. Finally, as long as Ukraine is seen as aligned with NATO, Russia feels compelled to direct the bulk of its forces towards its southwestern neighbor. If Ukraine were instead neutral, Russia would have to divide its attention between Ukraine and the more powerful NATO alliance, while still securing its huge territory and many borders. Armed neutrality would allow Ukraine to turn Russia’s unenviable security environment to its advantage, leaving Ukraine to face only a fraction of Russia’s total fighting potential at a given time.
Critics of armed neutrality suggest that even this approach will be a deal-breaker for Putin. Some Russian leaders, like Foreign Minister Sergei Lavrov, have suggested that a fully “demilitarized” Ukraine is a requirement for an end to the war. But Russia seems unable to achieve this maximal objective on the battlefield, and Trump therefore has room to maneuver. There may be incentives Washington could trade for Russian flexibility on military aid to Ukraine, including sanctions relief or willingness to discuss other Russian priorities, such as the U.S. role in Europe’s security. Russia could be offered assurances on the types of aid the United States and Europe would provide Ukraine — excluding intermediate range missiles, for instance. Moscow and Washington could also probably agree to prevent Ukraine from acquiring an independent nuclear deterrent. Geographic limits for both Russia and Ukraine on troop deployments or long-range strike systems might also help grease the wheels. Ultimately, haggling would be required, but a mutually acceptable deal is a realistic goal.
NATO’s Existential Choice
In addition to being Kyiv’s best option, Ukrainian armed neutrality is also the best option for NATO — especially its eastern-most members who have made Article 5 the foundation of their security. Unlike extending NATO membership to Ukraine or offering Kyiv a U.S.- or European-backed security guarantee, armed neutrality does not further threaten the credibility of the alliance’s mutual defense commitment or overburden its members with another resource-intensive and binding obligation.
Armed neutrality will not be cost-free for NATO, however, as allies will have a near- and medium-term responsibility to help build Ukraine’s military capabilities. Armed neutrality is also not a cure-all for the challenges Russia’s invasion of Ukraine has laid at NATO’s doorstep. The alliance’s initial response to the Russian invasion seemed to demonstrate that NATO had rediscovered a sense of common purpose. Over time, however, the war has pushed to the forefront the underlying tension that NATO’s eastward expansion introduced into the alliance. The ability of NATO’s original members to defend new entrants — especially the Baltic states — has always been more limited than they were willing to admit. Invading Ukraine in 2022, a resurgent Russia forced NATO members to grapple with the true cost of an expanded Article 5 commitment. Although Ukraine’s alignment has been more contentious for Russia than that of the Baltic states, owing to Ukraine’s core position in the Soviet Union and within Russian history and culture, countries on NATO’s northeastern flank may have new questions about Article 5’s durability after watching NATO waver over how and whether it could afford to support Ukraine.
Going forward, the tasks of ensuring NATO’s endurance and translating Ukraine’s armed neutrality into a long-term peace will fall largely to Europe. In particular, NATO’s European members will have to build military capabilities that allow them to match with hard power their growing commitments, including the Article 5 guarantee to the alliance’s eastern members and required support to Ukraine. These obligations cannot continue to be handed off to the United States, which has already indicated — if not in words then in deeds and actions — the limits of its willingness to defend “every inch” of NATO territory and its finite interests in Ukraine. If Europe does not step up, not only may Ukraine’s peace be short-lived, but worse, NATO itself may shatter under internal and external pressure on its Article 5 promise.
Ukraine’s armed neutrality is the best chance Brussels and Kyiv have for a lasting peace settlement that also preserves NATO, even if it falls short of what some hoped for early in the war. By offering Ukraine armed neutrality but no formal security guarantees, NATO members can prevent further damage to the alliance’s credibility and ensure that the alliance emerges from the Russo-Ukrainian war battered but not broken.
Jennifer Kavanagh is director of military analysis and a senior fellow at Defense Priorities. She is also an adjunct professor at Georgetown University.
Christopher McCallion is a fellow at Defense Priorities.
Image: Midjourney