Since 1999, Europeans have successfully launched and developed a European Security and Defence Policy. Concurrently to this strategic breakthrough of the European Union, they have contributed to their own collective defence for decades within the NATO framework and conducted a significant number of multilateral defence co-operations. What is the core of the European defence project and is there a roadmap according to which is it developing in order to tackle current security challenges? What are the main drivers that lead the Europeans to act together and how effective are they in the field of international security? For the first time, a French naval officer and a Franco-British defence analyst jointly set about identifying problems between the main players and the avenues to explore in terms of European Defence.