The war in Ukraine has highlighted many uncertainties and raised many questions concerning Europe’s future security and defence requirements. Has the world now been forced to accept that interstate war is no longer a phenom- enon of the past? Have the EU’s relations—and hopes for partnership—with Russia irrevocably ended? Has a new eastern-leaning centre of gravity been established within the EU? How has the war affected the nature and trajec- tory of transatlantic security relations? How might the EU conceptualise and deliver on its new requirements in the field of military capacity? What are the prospects for a peace settlement and a new Eurasian security order? These profound questions require a major aggiornamento in the EU’s approach to security and defence policy.