Russia’s unprovoked war against Ukraine has transformed the strategic culture that has supported and shaped the development of European security and defence cooperation over the past year. The EU has shown remarkable unity in the face of Russian aggression and agreed to unprecedented sanctions and other restrictive measures. Germany has announced that it will massively increase its defence spending and in an unprecedented move, the EU has also agreed to provide a €450 million lethal arms support package to Ukraine. Given the massive paradigm shift in European defence cooperation that Russia has caused, we need to reflect on what more could be done to ensure that Europe is able to respond to the various threats and challenges that it is facing, and for which it has the means and capabilities to support its partners. Could the creation of a ‘European Legion’ or a ‘European Army’ be a viable solution? What would such a structure look like? How is the operational dimension of European defence cooperation likely to develop following the adoption of the Strategic Compass?