How Europe Can Deter Russia
Deploying Troops to Ukraine Is Not the Answer
Barry R. Posen
April 21, 2025Ever since U.S. President Donald Trump began his effort to settle the war in Ukraine, European leaders have tried to assemble a military coalition capable of defending Kyiv. They have promised, specifically, to station forces in Ukraine. “There will be a reassurance force operating in Ukraine representing several countries,” said French President Emmanuel Macron in March. British Prime Minister Keir Starmer called for a “coalition of the willing” to help protect Kyiv.
This initiative may seem novel and bold, but it is old-think disguised as new-think. Europeans can call these forces whatever they want—peacekeepers, peace enforcers, a reassurance force, a deterrent force. But European leaders are simply repackaging NATO’s 1990s Balkan peacekeeping model for Ukraine. Penny packets of military force would be spread around the country to send the Russians a deterring message. Yet these forces would have limited combat power, and their credibility would depend on the promise of U.S. military force in reserve. European leaders even admit that their forces must be “backstopped” by Washington, which could provide massive air support in the event that the continent’s ground troops are attacked.
The scheme depends on Trump’s support and Russian President Vladimir Putin’s acquiescence. And both of them have already rejected their appointed roles. Trump is no more likely to commit the United States to wage war in Ukraine under any circumstances than was the Biden administration, which refused to do so. Moreover, the European plan would also have the effect, almost surely intended, of anchoring a wayward United States back into NATO, a project that U.S. Vice President JD Vance has repeatedly and categorically rejected. To Putin, meanwhile, acceptance of the European scheme would mean abandoning a key war goal—keeping Ukraine out of NATO and NATO out of Ukraine. European leaders get high marks for diplomatic subtlety as they attempt to disguise this two-pronged effort to rescue victory from the jaws of defeat. But it is very unlikely that either Putin or Trump will bite.
Even if Trump and Putin were to accept such a scheme, Europeans should not want to pursue it. The continent’s people face many potential threats from Russia, so it is foolish for them to tie down their readiest forces in garrisons across Ukraine. They may deter Russia there, but the forces would be unavailable for anything else. This kind of mission would lure European armies into rotating units through these positions in a way that doesn’t leave their soldiers far from home for long periods. Every unit will either be getting ready to go to Ukraine, be somewhere in Ukraine, or will just have returned from Ukraine. This routine is not a formula for a combat-capable army.
So what should Europe do, not only to deter future Russian threats to Ukraine but also to improve its ability to deter Russian aggression in the continent’s east and southeast? The answer is simple—Europe must organize what military planners call a “mass of maneuver” that can quickly deploy where it is needed. Europe cannot know in advance whether a refreshed Russia would renew attacks on Ukraine, move forward into Belarus, threaten Poland, or snarl at the Baltics. As a result, its officials must consolidate meaningful combat power that can intervene quickly wherever and whenever needed. That means they must stop distributing European military forces over the continent’s east and southeast simply as symbols of their commitment, linked to a U.S. cavalry that may no longer ride to the rescue. Rather, they must conceive of European military formations as scarce, expensive, and potentially lethal combat power, which can be deployed as a concentrated fist with the ability to fight independently, under either a NATO or an EU banner.
Contrary to what is widely believed, Europeans have most of the military wherewithal needed to create such a force. The question is whether they have the will.
ARMED, NOT READY
In their Trump-induced panic, European military leaders and pundits have spent the last few months talking about all the combat power that Europe does not have. But they have failed to evaluate and consolidate the combat power that Europe does have. For example, General Mikhail Kostarakos, the chair of the European Union Military Committee, observed that Europe lacks the “strategic enablers that would render it capable of independently performing the full range of tasks associated with the missions and operations it launches”—such as airlift and aerial refueling; intelligence, surveillance and reconnaissance; satellites; and air and missile defense. But Europe does have many of these systems, just not as many as commanders would prefer. Europeans may not have spent what the United States or NATO itself asked of them over the last decade, but they have spent hundreds of billions of euros. They have hundreds of thousands of people under arms and possess meaningful numbers of ground, air, and naval units.
Europeans, in other words, have combat power. To deter and defend themselves, what they need to do is consolidate that combat power and either deploy it close to the possible areas of a Russian challenge or at least demonstrate that they can do so in short order. In the first instance, this means being able to reinforce Poland, which by reason of size, location, and topography is both the eastern linchpin of European defense and the ideal base from which to counter Russian threats against the Baltic states and the continent’s southeast. It is also the ideal place from which it can intervene in Ukraine, should Europeans choose to do so.
To achieve this aim, the continent should fulfill the NATO Readiness Initiative, a proposal spearheaded by Jim Mattis, who served as U.S. secretary of defense from 2017 to 2019. This initiative called for NATO to develop the ability to deploy 30 battalions, 30 squadrons, and 30 ships to eastern Europe in 30 days. These four 30s were never achieved, even when the United States almost surely would have been a key contributor. It might thus be hard to see how Europe will succeed now. But much of the problem then was that Europeans were simply not scared enough to do their part. They are scared now, and that energy can be harnessed to fulfill the initiative and do even more.
European ground forces vary in their readiness.
The continent has the forces: European members of NATO collectively field nearly 100 fighter squadrons, 100 major warships, and over 100 brigades—of which it would need ten to meet Mattis’ 30-batallion objective. Ground forces are the long pole in the tent, but Europe’s air forces are large, modern, experienced, and well trained. They can provide powerful support to ground troops.
Some might argue that ten brigades is still not much force compared with the 90-odd regular and 80-odd irregular regiments in the Russian army. (A Russian regiment is similar to a European brigade, albeit usually smaller, less well-supported, and often understrength because of combat attrition.) But properly organized, ten good brigades, split into two mechanized corps, would be a capability that a Russian campaign planner could not ignore. For comparison, this force would be similar in size to the force that NATO planners encouraged Ukraine to concentrate for one attack in their 2023 counteroffensive in Zaporizhzhia. (The Ukrainians ignored this advice, divided their forces, and instead launched two weak offensives.) It is several times the size of the force that Ukraine thrust into the Kursk region of Russia in 2024. And it is about two-thirds of the size of the force that conquered all of Iraq in 2003.
Between them, the three key military players in western Europe—France, Germany, and the United Kingdom—field some 22 combat brigades, so they are well able to fill out the initial force on their own and, if need be, enlarge it. Although not all these brigades are tank-heavy armored units, they are all well-equipped by the standards of the Russian and Ukrainian troops that have fought one another to a bloody standstill in the last three years. This ten-brigade force would reinforce the Polish army, which according to the International Institute for Strategic Studies, itself has 14 brigades. A reinforced Poland would then become a tough nut for Moscow to crack, fielding roughly as many forces as Ukraine deployed to stop the Russian offensive in Ukraine in early 2022.
European ground forces do, however, vary in their readiness. Some of their equipment may need maintenance, and some units are understaffed. Munitions and spare parts, about which there is generally little public information, are almost surely not plentiful. And these forces would benefit from additional, short-range air defense systems that can handle the kind of drone attacks that are common in the war in Ukraine. Thankfully for Europe, rectifying these problems is straightforward: allocate more funds, double and triple shift the continent’s defense factories, and abandon the obsession with sharing defense spending and industrial work equally across borders. European military planners have already done some of this, but they must to do more.
NEED FOR SPEED
In addition to readiness, mobility is a problem for the continent. If Poland is to be the fulcrum of a large-scale European crisis reinforcement effort, then Europeans have to figure out how to get there. Skeptics complain that Europe lacks the airlift capacity to rapidly move forces around Europe, but this is a rhetorical diversion. No one, including the United States, uses airlift to move this much armor. Instead, armor mostly moves by rail, sea, and road. NATO planners and European Union officials know what needs to be done to get the continent’s infrastructure ready for such a task: strengthen bridges in eastern Europe, complete the integration of eastern European railroads with the rail network in the west, acquire diesel locomotives to pull trains if electrical power is interrupted by enemy action, and improve port facilities for the shipment and unloading of military cargo.
Some of these preparations are already underway. Several bridges in western Poland have been strengthened in recent years to accommodate heavy military loads. More broadly, the European Union has spent at least 15 years funding a major effort to upgrade Europe’s transportation infrastructure and has spent or committed over $38 billion to the effort. But this endeavor remains incomplete, and it should be accelerated. The European civilian-trucking industry, which is massive, should also be organized so it can support the movement of military goods to eastern Europe. (During the Cold War the West German army had the right to requisition 90,000 individual pieces of civilian heavy equipment.) To further enhance the credibility of Europe’s commitment to reinforce its eastern and southeastern members, reception and sustainment facilities can be improved across both areas. This means strengthening and building fuel tanks, skeletal bases with paved parking areas and bunkers, fiber-optic cables, and even railway sidings to permit rapid unloading of trains. Civilian and military airfields in eastern and southern Europe would benefit from similar kinds of improvements. These efforts can be managed by European civilian construction, manufacturing, and transportation firms.
Finally, it is critical for European military planners to concentrate combat power. He who defends everything defends nothing, or so the saying goes. The continent should be focused on being able to deploy to Poland, on short notice, one or two independent corps with accompanying air support—both of which must be able to operate without U.S. assistance. (A corps is the principal command organization for large ground force operations, coordinating the actions of five to ten brigades to achieve a common purpose.) The preparations that NATO has already made to reinforce Poland in a crisis can serve as the foundation for a repurposed, independent European effort. The existing NATO Multinational Corps Northeast, located in Poland and currently focused mainly on the Baltics and the Belarussian-Polish border, could serve as the foundation of one corps. The EU’s Eurocorps headquarters in the French city of Strasbourg could serve as the foundation of a second corps. The EU corps, a unit independent of NATO, should start to master the challenge of managing large field operations without American help. This corps should serve as the test bed for employing existing European command and control, navigation, and intelligence satellites.
Contrary to public perception, the continent has all these capabilities, even if they are not plentiful. Individual European nations are also accustomed to keeping their national hands on them. They share intelligence grudgingly. This must change. France and the United Kingdom, meanwhile, will need to think hard about how their nuclear forces can backstop the continent’s conventional forces in an independent European deterrence strategy.
If Europeans want to deter Russia, reassure Ukraine, defend existing EU or NATO members, or even defend Ukraine, then they need combat power that can match to the challenges posed by Russia’s military. This means assembling a capable mass of maneuver that makes Moscow more cautious when it comes to the continent in every which way. Peacekeeping with American help is old-think. Independent combat capability is the necessary new-think in Europe.