As the United States lessens its military support to Europe, Europeans will have to adapt the continent’s defense frameworks and architecture. With or without a ceasefire in Ukraine, Russia will remain the main source of European insecurity in the years ahead. There are three main models for Europe’s future defense architecture: a more European NATO, in which Europeans assume primary responsibility for conventional defense but are backstopped by U.S. nuclear guarantees; a European defense union, in which the European Union develops its own defense structure; and a European defense coalition, in which an ad hoc coalition of European states, including Ukraine, assumes responsibility for the continent’s defense.
Each model has different military, political, legal, and industrial implications, both for Europe and the United States. No single model offers a complete solution for the future of European defense, and some combination of the three is the likeliest outcome. A more European NATO would allow for the most continuity, but a European defense union would be a better option if the United States withdraws mostly or entirely from the continent. A European defense coalition, for its part, offers the greatest flexibility, but the lack of centralized planning and decision-making architecture could prove costly in times of crisis. European leaders should think of these frameworks as complementary, not mutually exclusive, while focusing on defense investment, capability development, and defense industrial expansion. A European defense coalition, based on a durable group of willing European states, including Ukraine, could provide the necessary political flexibility that neither a reformed NATO nor the EU could in a crisis, but would need to be complemented by more permanent support structures from NATO or the EU.
Council on Foreign Relations, co-authored with Liana Fix
