On January 1st, 200, the Treaty on the system « Open Skies » was enforced. This long-awaited Confidence-and security-building measure rests on the codified aerial surveillance of practically all territories of states members of the OSCE, from the Atlantic to the Ural. A pure product of the Cold war, « Open Skies »’s aim is to reduce suspicion between the States party. The instability that reigns today in some regions, the complementary character of the system in relation to the Treaty on the Conventional Forces in Europe (CFE) and the possible and future opening of « Open Skies » to new tasks, thanks to the new technologies of aerial surveillance, offer this Treaty new opportunities. –Summary AFRI-2003