The transformation of the international system, which took place during the 90s, has had direct consequences on the concept of intervention. Generally considered illegal, and as a clear expression of a power policy during the Cold War, intervention has been on the way to normalization for the past ten years. In fact, intervention undergoes the evolution of a system as much as it emphasizes its trends. The concept is simultaneously at the center of the debates on the existence of an « International Society », but also on the role of the State in the International Scene, on the concept of sovereignty and, therefore, the distinction between internal and external environment. Intervention is a crisis management tool contributing to the weakening of State sovereignty, and at the same time stigmatizes the ability of the Western States to cope with the breaches of world stability. – Summary AFRI-2001