Europe is preparing for its future security with little or no help from the United States. And in many such scenarios that European planners are now gaming out, Ukraine emerges as the linchpin of the continent’s defense. The weaker Washington’s security guarantee becomes, the more Europe needs Kyiv. Soon, Europeans will have to confront an entirely new burden-sharing question: What must they offer Ukraine for its help shielding Europe from Russia?
Until recently, European leaders could barely disguise their dread at the prospect of another acrimonious NATO summit, set to take place in Ankara in early July. The wounds are still raw from recent trans-Atlantic fights—including over U.S. President Donald Trump’s tariffs, his attempts to coerce Denmark to hand over Greenland, and recent U.S. troops withdrawals from Europe. Trump’s war against Iran and his accusations that European allies were insufficiently supportive of their principal security guarantor added to these wounds. This month, U.S. Secretary of State Marco Rubio ominously warned: “I think the next meeting of NATO … is probably the most important meeting in NATO’s history because there are some things here that need to be cleared up and fixed.”
Europe is preparing for its future security with little or no help from the United States. And in many such scenarios that European planners are now gaming out, Ukraine emerges as the linchpin of the continent’s defense. The weaker Washington’s security guarantee becomes, the more Europe needs Kyiv. Soon, Europeans will have to confront an entirely new burden-sharing question: What must they offer Ukraine for its help shielding Europe from Russia?
Until recently, European leaders could barely disguise their dread at the prospect of another acrimonious NATO summit, set to take place in Ankara in early July. The wounds are still raw from recent trans-Atlantic fights—including over U.S. President Donald Trump’s tariffs, his attempts to coerce Denmark to hand over Greenland, and recent U.S. troops withdrawals from Europe. Trump’s war against Iran and his accusations that European allies were insufficiently supportive of their principal security guarantor added to these wounds. This month, U.S. Secretary of State Marco Rubio ominously warned: “I think the next meeting of NATO … is probably the most important meeting in NATO’s history because there are some things here that need to be cleared up and fixed.”
U.S. Secretary of State Marco Rubio speaks at the NATO foreign ministers’ meeting in Helsingborg, Sweden, on May 22.Jonathan Nackstrand/AFP via Getty Images
Concerns about a fracas at next month’s summit have subsided somewhat. The apparent U.S.-Iran cease-fire deal, the announced reopening of the Strait of Hormuz, and Europe’s offer to help police the strait once a final peace agreement is reached have lowered the temperature. The friendly tone of this month’s G-7 summit in France, where Trump seemed on his best behavior, was another welcome sign. Cue the longtime trans-Atlanticists, who will surely argue that this proves the enduring resilience of the U.S.-Europe partnership—and that another near-death experience for NATO has been averted.
Such thinking, however, misses how rapidly European views of the trans-Atlantic alliance are changing. To the continent’s policymakers, NATO resembles Schrödinger’s fabled cat—simultaneously alive and dead. They treat the alliance as alive in the sense that they still do and say all the things they did before to demonstrate that they believe in its existence, not least to deter Moscow. But they also view it as dead in the sense that they can no longer rely on Washington as before.
European leaders are making plans to secure their continent without U.S. help. They no longer take seriously the assurance from Matthew Whitaker, the U.S. permanent representative to NATO, that a U.S. drawdown will leave no “strategic gaps.” They have given up on the idea that the Trump administration will agree to a road map for handing off Europe’s conventional defense in a predictable, coordinated way. So they are improvising. At the European Union level, officials are war-gaming how Article 42.7—the bloc’s closest equivalent to NATO’s Article 5 mutual defense clause—might be invoked if NATO is paralyzed. Leaders are asking what happens if NATO’s command-and-control structure simply isn’t there. Paris and Berlin have set up a nuclear steering group to discuss the possible role of the French nuclear arsenal in Europewide deterrence.
A demonstrator holds a sign reading “Europe, can you protect yourself?” at an anti-Putin protest in Berlin on March 1, 2025. Hannes P Albert/dpa Picture-Alliance via Getty Images
What stands out across many of these planning exercises is Ukraine’s role at the center of European security. Bolstering Europe’s own defense and deterrence as Washington’s commitment wanes will take many years. In a scenario exercise that the Council on Foreign Relations recently held with European officials and experts (which we both designed and in which one of us participated), it became readily apparent that Ukraine is the bulwark for Europe’s defense at a time of U.S. retreat.
In our exercise, set in 2029, the starting point for participants was a brittle cease-fire in Ukraine and an isolationist U.S. government seeking normalization with Russia while further pulling away from NATO, including by withdrawing the U.S. supreme allied commander from the bloc’s Belgian headquarters. Convinced that the United States will not come to help, Russia senses an opening and progressively escalates against Europe: first, by demanding negotiations on the basis of the Kremlin’s December 2021 treaty drafts (which, among other things, called for NATO to effectively withdraw from 14 countries in Eastern Europe and the Balkans) and then by escalating with conventional attacks and nuclear threats. In our exercise, the United States would stay detached and demand that Europe negotiate with Russia.
European participants had to decide how to react to U.S. passivity and Russia’s escalating attacks. Some Europeans initially tried to keep Washington on their side and continued to engage as they deliberated their response. British and French participants took the lead, while some Europeans were cautious and fearful of escalation with Russia without the United States by their side. Predictably, judging whether the escalation of Russian aggression reached the threshold to invoke NATO’s Article 5 was another source of contention among the more than 10 European NATO countries represented in the exercise.
Managing and coordinating an escalation ladder that could lead to the use of nuclear weapons without the United States was a huge challenge. As Washington was obstructing NATO involvement, European participants mostly chose coalitions of the willing as the format of coordination. They did not see the EU as a relevant mechanism in a fast-moving security crisis. However, their ad hoc coalitions had no decision-making structures in place, which could obstruct or slow down the European response in an actual crisis.
Participants were unified in rejecting Russian negotiation offers as lacking credibility and good faith. Although they agreed on the need for military-to-military contacts to avoid unintended escalation, any negotiation with Russia on the basis of its 2021 demands had little appeal for European participants, even as Washington nudged them to negotiate. A key Kremlin demand—stopping all support for Ukraine and leaving it to Russia’s control—was not even considered during the exercise. It was clear to participants that if Ukraine fell, Europe would be next. Many participants were hopeful that China could put a stop to Russian nuclear blackmailing.
As the scenario developed and the Europeans developed their responses, they relied heavily on Ukraine as a launchpad for offensive counteractions in response to Russian attacks on NATO territory, potentially including a reopening of the front in Ukraine. In the exercise, the Ukrainian side suggested that their forces could also play a role in defending Europe’s eastern flank.
The exercise demonstrated that Ukraine plays a crucial role in Europe’s future security with less U.S. support. In peacetime before any future crisis, Ukraine can pin down Russian forces and buy time for Europe to rebuild its own capabilities. The integration of Ukraine’s defense industry with its European counterparts is critical for Europe’s future defense. In case of war, Ukraine fields the most powerful conventional land army in Europe, hardened by years of high-intensity combat. Its drone, air defense, and artificial intelligence capabilities are battle-proven in a way no European arsenal can claim.
Newly recruited soldiers of Ukraine’s 159th Separate Mechanized Brigade take part in military exercises at a training ground near Kharkiv, Ukraine, on May 14.Yevhen Titov/Global Images Ukraine via Getty Images
Already in the current war, the balance of burden and benefit is shifting. It is still Europe that is keeping Ukraine in the fight. Europeans are largely filling the gap left by Washington’s stoppage of almost all military aid, either supplying weapons themselves or buying them from the United States, including the air defense interceptors that have grown scarce since the Iran war began. From January to April, European countries committed roughly 2 billion euros per month in new military support for Ukraine on top of the 90 billion euro financial lifeline they have provided to Ukraine.
Increasingly, however, defense support is a two-way street. Drone technology—including rapidly expanding joint production inside and outside Ukraine—is moving to the center of Europe’s military relationship with Kyiv. Europe’s drone-related funds for Ukraine have quadrupled from 400 million euros in 2022 to 1.6 billion euros in just the first four months of this year. This, of course, helps Ukraine but is also very much in Europe’s self-interest. Since the Russian drone incursion into Poland last September and the weak U.S. response to it, Europeans feel more exposed than ever. The further the United States pulls back from Europe, the more the importance of Ukraine not just for drone technology but as a conventional security provider comes into sight.
There was a time when some Europeans regarded Ukraine’s war effort with condescension and saw Europe’s help as charity, even as they admired the improvised but powerful means by which Ukraine held off the Russian war machine. Armin Papperger, CEO of the German arms manufacturer Rheinmetall, not so long ago dismissed Ukrainian drone defense as “play[ing] with Legos”—somehow not comparable to the high-end technology of the Western defense industry.
A Ukrainian soldier rests next to two UEB-1 interceptor drones near the front line on the outskirts of Sumy, Ukraine, on June 13.Francisco Richart/Anadolu via Getty Images
European military planners know better than to be that arrogant. They understand that Ukraine is holding the line for them—and that an end to the current war would free up Russian troops to threaten NATO’s eastern flank. The Europeans know that their own armies could not endure even a few weeks of the attritional drone warfare that Ukrainian soldiers engage in daily. Meanwhile, the credibility of NATO’s conventional deterrent erodes with every Pentagon announcement of another reduction of U.S. forces and capabilities available to respond in a European crisis. All of this increases the temptation in Moscow to test the alliance.
Europe’s weak position increases Ukraine’s value. The more the United States retreats, the more Europe needs Ukraine, and the more justified Ukraine’s demand for something in return, such as full EU accession, becomes. Ukraine is well aware of its newfound value; at this month’s G-7 summit, Ukrainian President Volodymyr Zelensky insisted on fast-tracked EU membership for his country: “Not all the leaders love such [a] format—fast track—because they want very understandable, clear steps for everybody. But we are not everybody, with all respect. … We are [at] war, and we need more creative steps.”
In time, even NATO membership for Ukraine comes into view, should the alliance become a European-led one with no role for the United States or less of one. Ukraine still lacks the nuclear, air, and naval power of France and Britain. But in the fight against Russia, no European state is as strong. As our scenario exercises have shown, there is no imaginable future defense architecture for Europe without the United States in which Ukraine is not a key element.
With NATO as we know it in limbo, the urgent task is to accelerate Ukraine’s integration into European defense, whether formally through the EU or as part of a coalition of the willing. The burden-sharing conversation Europe needs to have is not the familiar one about the cost of supporting Kyiv. It is about the burden Ukraine already carries not only to defend its own territory but also to shield a continent that is still far from ready for the day when the United States walks away. European leaders should start asking what they can offer Ukraine—not what Ukraine owes them.
