The ‘Ventotene spirit’ is more alive than in past every decade, notably more than during the decades of the Cold War and in the years of the illusions following 1989. Prioritizing the objective of a European political unity and methodologically addressing the link between ideational background and institution-building, is the double lesson and the legacy of Spinelli. Why and how could steps towards a European political unity be made in the coming years? The paper is shared in three parts: firstly, the objective, external, international conditions for the EU as a distinctive kind of international power are emerging in spite of multipolarity, power politics, fragmentation and bifurcation. Secondly, the subjective conditions are listed and critically evaluated. After a literature review about the nature of the EU international actorness, the paper focuses its third section on the multiple necessary features for the ‘open strategic autonomy’ asserted by the EU authorities since a decade. The institutional conditions are particularly underlined, as well as the alternative scenarios beyond the status quo: either a treaty reform or a political initiative within the current treaty framework.