In the wake of the Second World War, Europeans quickly became aware of the dilemma they faced concerning their collective security, namely the balance between autonomy and dependence – fate and freedom of action. The debate over European cooperation and subordination of European defence to the Atlantic defence structure is thus old. It dates back to the first years of the Cold War with the creation of NATO in 1949. Even though the idea of a European defence took shape with the Treaty of Brussels (1948), the European Defence Community (1950) and then the Western European Union (1954), European security would remain, throughout the Cold War, under the umbrella of the United States, in a confrontation with Russia based on “mutually assured destruction”. These various defence cooperation initiatives were essential for countering the Soviet threat and are at the very core of the debate previously mentioned. Consequently, an analysis of these initiatives and the context within which they evolved can be valuable for understanding the major issues that European defence decision-makers faced at the beginning of the Cold War. Furthermore, both in the past and today, there is a domain pursuing the objectives ofbetter interoperability, non-duplication, and better efficiency in defence, balanced between the Atlantic and the European logics and, in fine, of major importance regarding strategic autonomy: armaments standardisation.