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TO’s Door to Ukraine
Foreign Affairs
Close NATO’s Door to Ukraine
Years of Empty Promises Have Not Helped Kyiv or Fostered Peace
June 20, 2025
Ukrainian President Volodymyr Zelensky at a NATO meeting in Vilnius, Lithuania, June 2025Ints Kalnins / Reuters
CHARLES KUPCHAN is Professor of International Affairs at Georgetown University and a Senior Fellow at the Council on Foreign Relations. His most recent book is
Isolationism: A History of America’s Efforts to Shield Itself From the World.
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President Donald Trump returned to the White House promising to end the war in Ukraine “in 24 hours.” Since then, his administration has badly mishandled diplomatic efforts to bring about a cease-fire. Trump underestimated Russian President Vladimir Putin’s determination to subjugate Ukraine and has consequently failed to confront the Kremlin with the coercive pressure needed to stop its ongoing aggression.
But amid its bungled Ukraine diplomacy, the
Trump administration has gotten one important strategic issue right: it is time to take NATO membership for Ukraine off the table. After years of promises to bring Ukraine into the alliance, Washington is finally changing course. In February, Defense Secretary Pete Hegseth declared that “the United States does not believe that NATO membership for Ukraine is a realistic outcome of a negotiated settlement.”
Taking membership off the table will make it easier to negotiate a cease-fire with Russia, whose legitimate objections to Ukraine’s entry into
NATO partially motivated its invasion in 2022. And the Trump administration, for its part, is not alone in opposing Ukraine’s NATO membership; despite past pledges, a consensus within the alliance to invite Ukraine to join has never emerged and is unlikely to materialize in the foreseeable future. Although they have spent the last three years arming Kyiv, NATO members have not put their own boots on the ground. In doing so, they have made it clear that the alliance does not believe that defending Ukraine should warrant war between NATO and Russia. Pretending otherwise only encourages Kyiv to futilely push for membership, weakening the Ukrainian leadership when it inevitably falls short. Instead, Ukrainians should be pursuing more realistic options for securing their future.
At this year’s NATO summit, which takes place next week in The Hague, the alliance should commit to providing
Ukraine what it needs to defend itself against Russia. But NATO should also seize the moment to make clear that membership is not in Ukraine’s future. Closing the door on Ukraine will allow Kyiv and its supporters to get on with the task of making other plans for providing the country the security it needs and deserves.
Since the end of the
Cold War, the world’s most formidable military alliance, which prevailed over the Soviet-led Warsaw Pact, has been adding new members to its ranks and moving highly capable forces steadily closer to Russian territory. Over seven waves of enlargement, NATO has grown from 16 members in 1991 to 32 members today.
Moscow objected to NATO enlargement as soon as the alliance hatched the idea in the early 1990s. In 1993, Russian President Boris Yeltsin warned against the alliance’s eastward expansion, arguing that Moscow “would no doubt perceive this as a sort of neo-isolation of our country in diametric opposition to its natural admission into Euro-Atlantic space.” Two years later, Yeltsin was more pointed with U.S. President Bill Clinton: “For me to agree to the borders of NATO expanding towards those of Russia,” Yeltsin proclaimed during a visit by Clinton to Moscow, “would constitute a betrayal on my part of the Russian people.”
Russian disgruntlement has grown in step with NATO’s ranks, especially after Putin took office in 1999 and pursued a more confrontational foreign policy. At the 2007 Munich Security Conference, Putin described NATO enlargement as “a serious provocation” and asked, “Why is it necessary to put military infrastructure on our borders?” The following year, the George W. Bush administration, despite the objection of Germany and other European allies, convinced NATO to declare at its Bucharest summit that Georgia and Ukraine would become members. Soon thereafter, Russia wrested control of two restive regions of Georgia, effectively preventing the country’s accession to NATO. Similarly, Putin’s invasions of Ukraine in 2014 and 2022 aimed, at least in part, at blocking its entrance into the alliance. In his address at the beginning of Russia’s “special military operation” in Ukraine in February 2022, Putin cited “the fundamental threats which irresponsible Western politicians created for Russia,” singling out “the eastward expansion of NATO, which is moving its military infrastructure ever closer to the Russian border.”
The
United States has consistently dismissed these objections. As he launched the first round of enlargement at NATO’s 1997 summit, Clinton argued that NATO’s open door would “erase the artificial line in Europe drawn by Stalin at the end of World War II.” Secretary of State Madeleine Albright attempted to assuage Russian concerns by arguing that NATO remained a “defensive alliance that . . . does not regard any state as its adversary,” reassuring Moscow that “NATO poses no danger to Russia.”
Washington and its allies continued to take this line during successive waves of enlargement and through both Democratic and Republican administrations. Indeed, as Russian troops massed on Ukraine’s border in early 2022, U.S. President Joe Biden insisted that “the United States and NATO are not a threat to Russia,” a claim echoed by then NATO Secretary-General Jens Stoltenberg. Secretary of State Antony Blinken reiterated that “NATO itself is a defensive alliance. . . . And the idea that Ukraine represents a threat to Russia or, for that matter, that NATO represents a threat to Russia is profoundly wrong and misguided.”
Yet such arguments are either geopolitically naive or disingenuous. It is entirely understandable that
Russia is reluctant to allow into its neighborhood an alliance that, although defensive, nonetheless brings to bear ample military power. Whether it is NATO’s best tanks and aircraft, long-range strike weapons, or installations collecting intelligence, NATO’s arrival in Ukraine would pose a threat to Russia by dint of its sheer proximity. Russia, including its exclave of Kaliningrad, already has five NATO members on its borders and many more in its neighborhood. But given Ukraine’s strategic location, size, and historical connections to Russia, Moscow is particularly adamant that it not join NATO’s ranks.
NATO’s arrival in Ukraine would pose a threat to Russia by dint of its sheer proximity.
Russia is hardly the only major power keen to keep rivals out of its neighborhood. In fact, Moscow’s objections to Ukraine’s accession to NATO should be readily legible to policymakers in the United States, which has throughout its history made it a priority to expel other great powers from its neighborhood. From the founding era into the twentieth century, Washington used a mix of diplomacy and coercion to push its European rivals out of the Western Hemisphere. Since the late 1800s, it has repeatedly resorted to military intervention to maintain its influence in Latin America.
Guardianship of the neighborhood continued during the Cold War, with Washington working hard to box the Soviet Union and its ideological sympathizers out of the region. The competition came to a head with the Cuban missile crisis, in 1962, which brought the two countries to the brink of war. More recently, State Department spokesperson Ned Price promised that the United States would “respond swiftly and decisively” after Russia mused about again deploying its troops in Latin America in 2022. Its own history fresh in mind, Washington should have been more attentive to Russia’s concerns about Ukraine’s membership in NATO.
These arguments by no means justify Russia’s 2014 and 2022 invasions of Ukraine, nor do they legitimize Putin’s imperial ambitions or his delusions about the unbreakable civilizational ties between Russia and Ukraine. But it is time for U.S. officials to recognize the geopolitical realities staring them in the face. As he explained why “Ukraine coming into NATO is not on the table” in May, Special Envoy for Ukraine and Russia Keith Kellogg admitted that Russian objections were “a fair concern.” Such sobriety and strategic prudence will come in handy as the Trump administration seeks to convince Putin to end the war.
LEADING THEM ON
Ending Ukraine’s bid for NATO membership would not only make it easier to negotiate a cease-fire, it would also be to shoot straight with Kyiv instead of continuing to make promises that will likely never be fulfilled. NATO’s 2008 declaration that Georgia and Ukraine would eventually become members was a compromise; the Bush administration wanted to move them toward membership, although European leaders feared that doing so would inflame relations with Moscow. The declaration’s formulation that the two countries “will become members” was designed to be aspirational and anodyne; NATO set out no timetable or concrete plan for the accession of either country.
But the mild language nonetheless had explosive consequences. Not long after NATO’s statement, Georgian President Mikheil Saakashvili provoked a violent clash with pro-Russian separatists in the South Ossetia region. The incident offered Russia an excuse to send in military forces and grab control of both South Ossetia and Abkhazia. NATO barely lifted a finger in response. Saakashvili, in the end, badly overestimated the West’s support.
Though it took a different path than Georgia, Ukraine has ended up in a similar position. Heading westward since the 2014 Maidan Revolution and Russia’s subsequent invasion of Crimea and the Donbas, Ukrainians enshrined their NATO aspiration in their constitution in 2019. But when Russia invaded again in 2022, although NATO countries rushed weapons to Ukraine, Ukrainian soldiers have been on their own.
Many NATO members understandably feel a moral obligation to continue honoring the pledge to extend membership to Ukraine. But the result has been dashed expectations and growing frustration. After President Volodymyr Zelensky issued a blistering statement calling NATO’s unwillingness to move ahead on Ukraine’s membership “absurd” at the 2023 summit in Vilnius, NATO edged forward, asserting that “Ukraine’s future is in NATO.” Again under pressure from Kyiv, the alliance in 2024 took yet another step, assuring Ukraine that its path to membership was “irreversible.”
But the rhetoric only misleads; Ukraine remains on NATO’s doorstep, encouraged to keep waiting outside but never allowed to enter. Kyiv is ultimately better off knowing the hard truth.
LOUDER THAN WORDS
Although they have yet to acknowledge it, member states have already taken a decisive step toward closing the door on NATO membership for Ukraine: they have made it clear through their actions that they do not deem it in their interests to go to war with Russia to defend Ukraine. Amid more than three years of fighting, around 500,000 Ukrainians have lost their lives or been wounded valiantly resisting Russia’s onslaught. The United States and its partners have provided close to $300 billion in military and economic assistance to Ukraine. But NATO countries have not dispatched a single soldier to join the fight, having concluded that defending Ukraine does not warrant a direct war between NATO and Russia. Their caution extends beyond the refusal to put boots on the ground. Ukraine’s NATO patrons have also carefully metered the lethality and range of the weapons provided in order to reduce the risk of escalation with Russia.
Alliance leaders may declare that Ukraine is fighting for the future of the West; that the war represents the frontline in the battle for democracy; that the defense of the rules-based order requires the expulsion of Russian troops from Ukraine; and that if Putin is not defeated in Ukraine, a NATO country could be next. But actions speak louder than words. Led by Washington, NATO has decided that the defense of Ukraine is not worth World War III.
Accordingly, NATO should not extend a security guarantee to Ukraine once the war ends, thereby obligating the alliance to go to war with Russia should it again invade. If Ukraine were attacked by Russia after becoming a NATO member, NATO could, of course, decide not to fight on its behalf. But failure to defend a member state would corrode the alliance’s credibility. In short, NATO would find itself in an impossible position: fight a war against Russia it has previously determined not worth fighting or stand down and irreversibly—and perhaps fatally—undermine the Western alliance in the process.
APART BUT NOT ALONE
Seeing its bid for NATO membership fail will be a harsh and painful reality for Ukraine as it continues to suffer ruthless Russian attacks. But putting an end to the illusion that Ukraine is on the path to NATO membership is by no means abandoning the country’s security. On the contrary, Kyiv will know where it stands, encouraging it to focus on more attainable goals.
Kyiv should concentrate on convincing Washington and other partners to keep the arms coming and make the most of the multiple bilateral security pacts that emerged from negotiations on the margins of NATO’s 2023 summit. Ukraine should also expedite its accession to the EU, a process that would speed up economic and political reforms and ultimately give the country at least a version of the security guarantee it seeks; Article 42.7 of the Treaty on European Union is a mutual defense clause. Moscow has indicated that it can live with Ukraine’s integration into the EU, which it sees as a more benign economic and political bloc, not a military alliance.
The proposal that has emerged from Trump’s diplomatic efforts is sound: a cease-fire, with Russia holding on to the roughly 20 percent of Ukrainian territory that it currently occupies. But that deal is acceptable only if the remaining 80 percent of Ukraine emerges as a sovereign, secure, and prosperous democracy. Arriving at that outcome will require that NATO provide Ukraine the military capability, training, and intelligence needed to block further Russian advances, enabling Kyiv to make it clear to Putin that he has already conquered as much of Ukraine as he is going to get. Ukraine is unlikely to give up on restoring its territorial integrity. But that goal should be pursued at the negotiating table with a post-Putin Russia, not on the battlefield. For now, Kyiv should focus on securing a durable cease-fire and turning a free Ukraine into a success story.
Taking Ukraine’s NATO membership off the table will make such a deal much easier to attain. Putin is more likely to end the war if he is confident that Ukraine will not thereafter join NATO. In return, NATO should demand that Russia agree to not only a permanent end to the war but also a renunciation of further territorial claims as well as any restrictions on Ukraine’s armed forces and its ability to defend itself.
A NATO consensus behind this plan may be elusive; some members, particularly along NATO’s eastern flank, remain keen to bring Ukraine into the alliance. Trump, however, should employ his trademark willingness to say out loud what others are thinking but not dare say, and acknowledge a simple truth: NATO membership for Ukraine is unattainable. He should make it clear that his administration is ready to provide Ukraine the help it needs to defend itself, but that when it comes to the country’s accession to NATO, the door is now closed.