Transatlantic Uncertainty and the Future of Ukraine

In early December 2025, the Fletcher Russia and Eurasia Program hosted a lunch seminar with Dr. Robin Brooks, Global Policy Fellow at Pomona College. Dr. Brooks previously served as Special Advisor to Vice President Kamala Harris for Europe, Russia, Multilateral Affairs, and Democracy, and as the National Security Council Director for Central Europe and the Balkans, as part of her more than 20 years in the U.S. Foreign Service. She was also the State Department Fellow at the Fletcher School and taught two courses here in the 2024-5 academic year.  Her December talk at the Russia and Eurasia Program examined U.S.-Europe relations in the context of Russia’s war in Ukraine and how recent U.S. policy signals have affected Transatlantic trust.

U.S.-Europe ties today

Dr. Brooks opened with an overview of the Transatlantic relationship over the past decade, noting that Russia’s invasion of Ukraine necessitated increased cooperation between the U.S. and its European Allies after several years of waning trust resulting from the U.S. pivot to Asia during the Obama Administration and later from perceived slights to Western European NATO members by the first Trump Administration. She noted the perception among many Western European Allies that U.S. rhetoric and policy from 2017-2020 had served to divide and weaken NATO, since it seemed to focus on domestic priorities of semi-authoritarian governments on the Eastern Flank, rather than on the Alliance’s core values and mission of defending democracies against conventional and hybrid threats especially from Russia. She noted that one of the Biden Administration’s first challenges upon taking office in 2021 was therefore to rebuild and strengthen relations with traditional allies and partners, and particularly with Western European countries on the basis of shared democratic values, while maintaining and deepening ties with Eastern European Allies. She laid out the challenges that made doing this hard.

Dr. Brooks then described how Russia’s unlawful invasion of Ukraine changed European security thinking. She described renewed cooperation under U.S. leadership on responses to Russia’s aggression, but highlighted the ongoing trust deficit that made progress slow. She noted that the inauguration of Donald Trump for a second term as president in 2025 spoke to the critical importance of enhanced European leadership to solve this conflict on the European continent.

The U.S. National Security Strategy as a Bellwether of Transatlantic Relations

Dr. Brooks noted the release of a new U.S. National Security Strategy (NSS) earlier in the week of her talk. She said many European allies found the new NSS unsettling, especially due to the apparent shift in the “values basis” for U.S. foreign policy (specifically a shift away from democratic values and human rights) and because of internal inconsistencies in how the document described the U.S. commitment to Europe’s security. She noted that the new NSS also differed sharply from all prior National Security Strategies, both in the listed goals and in the proposed means to achieve them.

Since Dr. Brooks had worked directly on U.S. strategy and policy towards Europe in the Biden-Harris administration, she was able to explain how the 2021 NSS was developed – through iterative interagency discussions of a range of interrelated challenges and opportunities – and how it was implemented, As an example of implementation, she shared her experience in 2021 developing sanctions packages under the Protecting European Energy Security Act (PEESA) against entities building the Nordstream 2 pipeline, which would have circumvented Ukraine to bring Russian gas directly to Germany. She then contrasted that to her informed understanding of how the current NSS was developed, and she analyzed what that change meant for Transatlantic relations. She assessed that the Trump Administration’s efforts to resolve the war in Ukraine seemed unpredictable or inconsistent to European Allies largely because the President was focused on the limited goal of delivering “peace,” without a clear vision for what that peace would look like. She described a national security apparatus in which, instead of iterative interagency deliberation, policy was determined by whatever the last person to speak to the President said.

Russia’s Invasion of Ukraine and Transatlantic Relations

Dr. Brooks noted that in the months before Russia’s 2022 full-scale invasion of Ukraine, the U.S. had to convince NATO Allies both that the invasion was about to happen and also that it was dangerous for European security. She described the challenges resulting both from Western European Allies’ lack of trust in the United States and from Allies general perception that Russia’s invasion would be swift and successful, such that “Kyiv would fall in three days” without a protracted war, and that it therefore would not affect European security very much. Once Ukraine proved capable and willing to defend itself, however, Dr. Brooks said European Allies began to see the need to cooperate on operational decisions. Still, the United States had to persuade Eastern European allies to host humanitarian and security hubs, since some feared that doing so would make their countries targets of Russian retaliation.

She said U.S. officials repeatedly had to explain why Ukraine’s territorial integrity mattered and why Ukraine’s survival was directly tied to Europe’s security. She noted that by the time many European governments agreed on key steps, public fatigue in their countries with the war and its impacts on their economies was already growing.

Dr. Brooks argued that the cautious, consensus-driven approach in the first years of the war often led to slow decisions and delayed delivery of material support for Ukraine, which reduced Ukraine’s ability to win quickly. She described this as a serious problem, but also said it was understandable given very real concerns about the potential for Russian escalatory retaliation, Congressional worries about public corruption in Ukraine, and the need for ongoing coordination with both Allies and President Zelensky. Nonetheless, Dr. Brooks argued that reliance on a facts-driven, interagency/intergovernmental, deliberative process resulted in better outcomes than any alternative process could have done.

What comes next

Dr. Brooks noted that some of the current administration’s policy decisions have potential to deter Russian aggression (or impose costs for it) and to strengthen the chances of peace – such as recent sanctions on Russian oil and gas principals Gazprom and Lukoil – but she warned that the possibility of weak enforcement or of sanctions being lifted for a suboptimal deal has been highly damaging to European confidence in the United States and to the broader Transatlantic relationship. She closed with what these trends mean going forward. She argued that ending the war on acceptable terms and reducing Russia’s ability to keep fighting requires one of two outcomes: either Ukraine receives credible security guarantees that deter future attacks, or Russia is defeated on the battlefield.

She also highlighted the debate over seizing Russian state assets held in Europe as another possible lever that remains disputed among EU member states. She argued that the new NSS points to a larger reality: Europe should assume the U.S. will be pulling back from leadership on supporting Ukraine’s defense, though it likely will sell weapons to Europe for transfer to Ukraine. She concluded that Europe needed to develop its own vision for the futures of Ukraine and Russia and to convince the United States to come along.  In doing so, she added, Europe also must manage internal “spoilers” that block common action, and it must treat Ukrainian security as inseparable from European security.