Europe’s security architecture is being remade in real time. Russia’s war against Ukraine and U.S. President Donald Trump’s return to office has challenged the basic premises on which European security rests. Europe is under threat from Russia and has lost the United States as its ultimate security guarantor.
Trump’s hostility toward NATO and ambiguity in relation to Article 5 means that Europe can no longer rely on the United States to come to its defense if Russia attacks. Despite Trump’s occasional feel-good rhetoric about NATO, his unpredictability and unreliability fundamentally undermine the credibility of U.S. commitments to Europe, which are central to NATO’s deterrence.
Reports of the United States planning to further reduce the number of its troops in Europe and cut security assistance to front-line states is testament to Washington’s withdrawal from Europe. On its way out, the United States may very well take Greenland with it—an act that would blow up NATO and bury any pretense that the United States is interested in European security.
Meanwhile, Russia is busy rearming and reconstituting its forces as it continues its war against Ukraine. The Kremlin sees itself already at war with Europe, though this has manifested itself mainly in so-called hybrid attacks across the continent. Russia has shifted to a war economy, on which it now spends around 40 percent of its budget. It aims to have an armed force of 2.38 million of whom 1.5 million would be active servicemembers. It produces 1,500 battle tanks per year, more ammunition in three months than NATO produces in a year, and claims to have successfully tested a nuclear-propelled cruise missile.
European leaders have begun to understand the seriousness of the situation, underlined by their commitment to spend 5 percent of GDP on defense and defense-related infrastructure. But rearming will take time, and the extent to which Europe’s major countries will be willing and able to fight is, at best, unclear.
What can Europe do to prepare for a world in which the United States doesn’t have its back and Russia may be preparing to attack?
The answer may be as obvious as it is controversial: Europe needs to bring Ukraine firmly into its security architecture. Battle-hardened, experienced, and deeply committed to resisting Russian aggression, Ukraine should no longer be seen as merely a recipient of security aid. Ukraine has the potential to be one of the most important security providers—perhaps the most important one—for the rest of Europe, especially as the United States withdraws from the continent.
In practice, Ukraine is already a significant provider of security for Europe. By fighting Russia and defending its right to exist as a free and democratic state, Ukraine is defending all of Europe. It is weakening Russia, tying down Russian troops, and acting as forward defense for NATO allies. Ukraine’s resistance is transforming how the continent conceives of its own defense. The question now is how to formalize and sustain that role within a broader European framework.
The logic of Ukraine’s present and future role in European security is incontrovertible. Since the beginning of the full-scale invasion in February 2022, Ukraine has fought back effectively, with Russia suffering at least 1 million military casualties. Ukraine has not only pushed back the invaders from vast territories in the north, east, and south, but it has managed to invade Russia and hold a significant part of the Kursk region for more than half a year. It has denied Russia air superiority and managed to hit targets more than a thousand kilometers inside Russia. Using drone and missile strikes, it is rapidly depleting Russia’s air defense assets. On the battlefield, Ukraine has destroyed more than half of Russia’s entire stockpile of tanks, infantry fighting vehicles, armored personnel carriers, and artillery systems.
Today, Ukraine has the largest military force in Europe after Russia, numbering around 900,000 troops. These battle-hardened troops have been carrying out NATO-core business—defense against Russian aggression—since 2014. Ukrainian troops understand Russia’s way of war and the new realities of drone warfare better than any NATO member.
Ukraine’s experience with cost-effective counter-drone measures is already coming to the aid of front-line NATO states, which have seen Russian incursions into their airspace. Ukrainian President Volodymyr Zelensky has offered Ukrainian counter-drone experts to Denmark after several drones—believed to be Russian—were spotted over Copenhagen’s airport. He has also offered Ukrainian know-how for the European Union’s plans to build a “drone wall” on its eastern border.
Ukrainians know how to use NATO weapons better than NATO troops do. Having used a motley mix of NATO systems, they understand precisely what works and what doesn’t in real combat. They have also had to find pragmatic fixes and workarounds when NATO weapons have not been as effective as expected. Ukraine is developing an impressive defense industry, specifically tailored to resisting Russia. European defense companies, including drone manufacturers eager to leverage Ukrainian expertise, have set up shop in the country despite the ongoing war.
How can Ukraine’s outsized role in defending Europe be formalized? A first step could be for Ukraine to become a security guarantor for the Baltic states. Given Russian revanchism and American disinterest, the vulnerability of Estonia, Latvia, and Lithuania is palpable. As a particularly exposed part of NATO’s eastern flank, they are under constant hybrid attack by Russia—most recently with incursions into Estonian airspace by three armed MIG-31s. It is far from inconceivable that Russia would choose one of the Baltic states to test NATO’s resolve and Trump’s willingness to defend an ally. As various analysts, intelligence experts, and defense planners have warned, Russia could pose a military threat to the Baltic states soon after the war in Ukraine ends or the fighting otherwise slows down.
A future offer of Ukrainian assistance could take the form of an iron-clad security guarantee by which Ukraine would consider an attack on one of the Baltic states as an attack on itself. This guarantee would be offered once Russia’s war against Ukraine has subsided; it is unlikely that Ukraine could spare troops for the Baltic states while it is defending itself against Russia.
This commitment would necessarily be one-sided. It would not mean that the Baltic states would commit to fighting Russia in case the latter resumes its war on Ukraine. This asymmetry would preempt objections from other NATO members who want to avoid Ukraine entering NATO through the back door. They would object to a commitment by the three Baltic NATO members to go to war with Russia if Ukraine is attacked again. Such an arrangement could quickly spiral into a larger war between Russia and all of NATO.
In practical terms, Ukraine would commit to sending troops to fight alongside NATO to defend the Baltic states. The security pact could also include the provision of weapons, ammunition, logistical support, and intelligence. A separate agreement with Poland would be necessary to ensure transit for Ukrainian troops and equipment to the Baltics.
After the end or stabilization of the current war, Ukrainian troops could also be stationed in Estonia, Latvia, and Lithuania alongside NATO forces. Ukrainian troops with combat experience could train and teach Baltic troops. The Swedish island of Gotland could also be used to host Ukrainian troops and preposition arms.
As another provision of such a security pact, Ukraine could reserve the right to attack Russia directly in case the latter attacks one of the Baltic states. This would no doubt be controversial, but it would not be different from other collective security commitments, such as NATO’s Article 5. Importantly, this would have major implications for Russian military planning, complicating Russia’s strategic calculations and raising the cost of any attack.
None of this would be a substitute for NATO. Future U.S. administrations may choose to reengage with the bloc, and even Trump could conceivably extend some form of support to the Baltics. The security pact should be seen as an additional security layer to that which NATO provides.
Even a one-sided security pact such as this would have several advantages for Ukraine.
First, it would underline the fact that Ukraine is not only a security consumer but also a security provider. This shift in narrative is important given the view in parts of the West, including the United States, that Ukraine is an ungrateful recipient of military assistance. A security pact would show that supporting Ukraine is not charity but rooted in a deep interest in European security.
Second, it would anchor Ukraine more firmly in Europe’s security architecture and show how it can play a central role in whatever future security arrangements emerge. The security pact could be a first step toward other defensive alliances between Ukraine and Europe’s front-line states, including the Nordic countries. Besides NATO, a future European security architecture may consist of a web of mutually reinforcing regional alliances.
Third, a security pact would require Ukraine to be included in NATO military planning for the Baltic states. This would advance Ukraine’s de-facto integration into alliance structures and further enhance interoperability, bringing Ukraine another step closer to NATO membership. It would strengthen Ukraine’s case for membership by showing how it can contribute to collective security.
Finally, such a move would come as a surprise, not least to the Kremlin. It would shift the framing of Ukraine’s role in European security. It would show strategic initiative and determination while putting Russia on the back foot.
Europe has woken up in a completely new world. Security provided for cheap by the United States, the foundation of European peace and prosperity since World War II, is no longer a given. While European leaders still hope that NATO can deter a Russian attack, alternatives have to be considered. Rearmament will take time that Europe may not have. The obvious solution is to bring Ukraine into Europe’s security architecture, and a security pact with the Baltic states could be a first step in this direction. It’s time to start discussing with Ukraine how to formalize the role it is already playing in Europe’s defense.
