Over a month has passed since Donald Trump’s election, and the war in Ukraine is escalating instead of ending. Various unverified proposals for negotiations have been floated to the press by the United States, Russia, and Ukraine, with little overlap between them. Mistrust of Russia is dominant and expected, but fears of the United States cutting a deal with Russia that is unfavorable to Ukraine are pervasive and counterproductive. Part of the problem lies in the unhealthy confusion between three interconnected but separate steps necessary to end the war: entering negotiations, reaching an agreement between Ukraine and Russia, and establishing a post-war security architecture in Europe to hold the agreement in place. 

The United States will likely intend to initiate direct talks with Russia after Trump’s inauguration. However, this cannot be expected to result in a deal with Russia without Ukraine and Europe’s cooperation. Even if negotiations commence, the war could still continue and intensify if Ukraine and Europe do not feel safe in a post-war environment. The worry of punishment or abandonment by the United States in case of non-cooperation cannot be ignored, and the solution to avoid such a situation is a frank U.S.-European dialogue and active engagement.

Despite the importance of territorial, political, and cultural issues to be negotiated between Ukraine and Russia, the core concern for both Ukraine and Europe is guarantees that war will not erupt again. There is a genuine fear that Russia will use the armistice to rebuild and attack in a few years. Russia might also have the same concerns about Ukraine and the West. Post-war security architecture, then, is the key to reaching a sustainable agreement in Ukraine. Before talking to Russia, the West must agree on measures to deter and incentivize sustaining any armistice. Despite the significant Western support for Ukraine since the war started, a credible security architecture for post-war deterrence has not been established. 

Any agreement on post-war architecture should reflect the security concerns and national interests of the parties to be reached and respected. But what if the Western concerns and risk profiles towards Russia differ?

Within the West, there is a mismatch between vulnerabilities, escalation risk tolerance, and capabilities. The vulnerabilities of the frontline countries (the Nordic countries, the Baltics, and Poland) are the highest due to their proximity to Russia, while their capabilities are the weakest, accounting for less than 5 percent of NATO’s total defense spending. The rest of Europe is less vulnerable to Russia but more capable, with defense spending comprising 30 percent of NATO’s total. 

The least vulnerable to Russia and the most capable is the United States, which accounts for roughly two-thirds of NATO’s defense spending. Vulnerabilities shape concerns and, consequently, escalation risk tolerance. Throughout the past two years, the more tolerant to escalation risk are the most vulnerable and least capable in case of a bigger scale total NATO-Russia. To navigate these contradictions, the United States and Europe can only agree on a post-war division of responsibilities if they can match the concerns with capabilities and escalation risk tolerance profiles. 

Between September and November 2024, over thirty-five experts and officials from the United States, EU, Western Europe, Central Europe, and frontline countries, including Ukraine, deliberated to identify post-war security concerns and discover commonalities and differences.

The first observation is that Trump’s approach to the world is not an anomaly but rather a reflection of genuine U.S. priorities, which do not always align with those of Europe and Ukraine. 

The U.S. experts prioritized the following issues as concerns in the post-war environment: preventing nuclear war with Russia in the medium to long term, reducing Russian support for and relationships with its adversaries (such as North Korea, Iran, and China), and limiting hybrid attacks on U.S. infrastructure domestically and internationally. These concerns do not seem radically different from those the Biden administration articulated or what Vice President Kamala Harris might have prioritized had she been elected. The concern over nuclear escalation also explains the low tolerance for risk-taking demonstrated repeatedly—and frustratingly to Europeans—by the Biden administration.

The second observation is that the top three U.S. concerns towards Russia post-war did not include any threats in Europe. That is significant and will shape the form and scale of any future American engagement in post-war security in Europe. Europeans may be further disturbed to learn that U.S. experts were not overly worried about losing credibility in the eyes of China if Washington lets Brussels and Kyiv down. According to said experts, the dynamics between China and Taiwan are complex, and China is more likely to draw lessons from Russia’s costly failures in Ukraine than from the specifics of U.S. responses. For U.S. allies, the support for Ukraine so far has demonstrated what the United States is willing to do for a non-ally under attack, signaling a baseline for its future commitments to formal allies.

The third observation is that post-war Europe is likely to remain focused on small-scale Russian provocations aimed at testing NATO’s credibility. Both American and European experts did not anticipate a full-scale Russian invasion of NATO territory, as such an action would be both costly and risky for Russia, which is expected to be cautious about repeating the failures experienced in Ukraine. However, the front countries are considered more vulnerable to provocations, such as Russia potentially assembling a small force to seize a limited area of the Baltics. While such an event was deemed unlikely in the short term, it was not dismissed as entirely implausible in the medium to long term. Meanwhile, the Western and Central European groups expressed concerns about potential war fatigue undermining long-term commitments to credible deterrence and sustained support for Ukraine in the post-war period.

A Post-War Deterrence Strategy Synthesis

The only overlapping concern toward Russia within the West was the continuation of hybrid attacks. Depending on whether the war concludes with an armistice or a de facto ceasefire, hybrid attacks, such as sabotage and cyberwarfare, could remain a concern for both the United States and Europe. Despite this commonality, the nature and intensity of these attacks are likely to vary between Americans and Europeans.

The lower priority attached to Europe in U.S. foreign policy does not mean a collapse of the relationship and cooperation. The United States and Europe can find common ground on key issues such as preventing the collapse of Ukraine, protecting NATO’s front-line countries from future aggression, mitigating hybrid destabilization activities, and curbing Russian support for Iran and North Korea. Ultimately, the United States and Europe share common goals of security and prosperity. Yet, they must find ways to collaborate effectively at a time when gaps in values and institutional approaches are widening.

Even if negotiations start, both the United States and Europe would be interested in preventing a Ukrainian military collapse Ukraine. Europe could propose plans to support Ukraine’s defenses by urgently increasing supplies from European stockpiles. While this carries political risks, it is less costly than the financial and political catastrophe of a Ukrainian collapse and the mass exodus of 6 million Ukrainians to Europe and other countries abroad. Regardless of the form of post-war arrangements, Europe will bear a higher share of the burden. To show seriousness and build trust, a more balanced burden-sharing scheme could be proposed. For instance, increasing European defense spending to 2.5-3 percent of GDP could demonstrate commitment. Collaboration with U.S. military producers on replenishing stockpiles and establishing joint production and knowledge transfer programs would strengthen Europe’s industrial base and align U.S. interests with long-term European security.

Given the current level of distrust, no agreement with Russia, regardless of the details, will secure Europe if its post-war deterrence is not credible. To enable Ukraine-Russia negotiations to start and facilitate an agreement, Europe and the United States should work towards a two-pronged strategy: a porcupine defense posture (e.g., air defense, counter-mobility) for Ukraine to deter and defend against any future Russian violations of an armistice, and an augmented deterrence-by-denial structure in Europe to increase the cost of any future Russian aggression against NATO.

This approach matches the differing concerns, levels of commitment, and risk tolerance profiles of the United States and European countries. It is also unlikely to impede Ukrainian agreements with Russia. Europeans do not intend to provoke Russia, and post-war deterrence planning is still unfolding. More importantly, the specifics of deployed systems will depend on the particular post-war threats, the terms of any agreement between Ukraine and Russia, and Europe’s capacity to produce and deploy such systems.

Risk reduction measures and potential arms control agreements with Russia could help stabilize the situation and communicate intentions clearly. This post-war security structure will likely progress as long as Russia remains uncooperative. However, if Russia engages in good-faith discussions with the West, it could shape the future security framework. The longer Russia remains disengaged, the more difficult it will become to account for its interests in Europe’s post-war measures and arrangements.

Managing Expectations

Despite these possibilities of engaging with the United States, Europe should not be surprised if Washington pursues its own agenda with Moscow. This will require both managing expectations and preparing for times when U.S. interests diverge from Europe’s. The challenge for Europe is to compartmentalize the issues and establish new rules for the relationship to minimize damage. The inevitable will be for Europe to take care of its own business and become more independent. But will Washington accept that? This remains an open question.