Europe Reinvents Its Security System—for the Short Term note: The author would like to thank the Norwegian Ministry of Defence for its support of his research on the impact of the Ukraine war on the security situation in East Asia. It would be a platitude to state that the Russia-Ukraine war has had a massive impact on the European security system, but it is essential to emphasize that the fast and profound reconstruction of this traditionally well-structured system addresses primarily the most immediate security challenges, while mid- and long-term problems remain clouded in uncertainty. Russia's aggression against Ukraine, unleashed on February 24, 2022, after eight years of violent conflict, produced a painful shock for most European politicians and publics. Although Russia, through its invasion of Ukraine, hoped to create confusion and discord among its neighbors, the European Union has risen to the challenge, recognizing the invasion of Ukraine as a direct threat to the security of all stakeholders in regional peace. The immediacy of this threat has brought together Europe's interest-based and value-based policies and focused them on the common goal of ending the war with a just peace, ensured by resolve to increase investments in collective security. Europe has sustained its remarkable unity behind the commitment to ensure Russia's defeat, as the proceedings of the 2023 Munich Security Conference confirm.1 Impressive as these efforts have been, however, perhaps inevitably they deal only with the foreseeable future, the horizon of which may turn out to be very close indeed. U.S. Leadership Is Too Good to Last The onset of Russian aggression toward Ukraine not only severely distorted European designs for cooperative architecture and plans for resource allocation; it also called into question the basic tenets of European security philosophy. The belief that profitable economic engagement makes Russia a conflict-averse, even if difficult, partner was ingrained [End Page 30] in traditional German Ostpolitik as well as in French preferences for cultivating dialogue with Moscow, Italian eagerness to turn a blind eye to the smoldering conflict in eastern Ukraine, and many other self-deceptive policies. The break with these illusions was swift and radical, and the German term Zeitenwende (historical turning point) is applicable to many decisive turns in European policymaking all the way from Finland and Sweden down to Greece and Cyprus.2 One prominent feature in this war-driven revision of European security thinking is the broad acceptance of and increased demand for U.S. leadership, so that the long-running, even if not particularly productive, debates on security autonomy have been momentarily reduced to irrelevance.3 U.S. president Joe Biden has succeeded in alleviating the worries about the reliability of the U.S. security commitment that were generated by the policies of his predecessor, and he has delivered on the promise to build an alliance of democracies capable of withstanding the pressure from revisionist autocracies. The U.S. initiative that established the Ramstein format for coordinating the supply of arms to Ukraine has been crucial in making every difficult decision—from the delivery of mid-range strike weapon systems (such as the M142 HIMARS) to forming the "tank coalition" designed to empower the Ukrainian army to make a new counteroffensive breakthrough.4 The states that have embraced re-energized U.S. leadership, like Poland, have found their role in the new war-centric security system strongly reinforced, despite their infractions of core European democratic values and tensions with influential neighbors, such as Germany.5 This reconfiguration of the security structure around U.S. leadership remains key to the goal of ensuring Ukraine's capacity to restore its territorial integrity, but it will become incongruous after this victory is achieved. The issue is not only that [End Page 31] the United States needs to direct more attention to its domestic agenda and more resources to the competition with China in the Indo-Pacific theater, both of which will necessitate a significant reduction of its engagement in European affairs from the moment of Ukrainian triumph; no less important is that there has been a strong increase in the EU security profile, which is currently overshadowed by the focus...