In May 1998, the European Commission adopted a program entitled “Global Monitoring for Environment and Security” (GMES), with the objective of establishing a comprehensive capacity for observing and reviewing the environment, in order to assess the risks related to human activities. Initially intended for the sole environmental security questions, GMES is widening its range to include more general security matters, thus acquiring a military dimension, which by the way is made explicit by its texts. This dual characteristic of GMES did not happen without provoking heated debates, essentially because the security notion, far from being definable, may recover a number of aspects : civil security, defence security. Thus, GMES provoked a question on its synergy with European military needs at a time when ESDP is being established. GMES has thus become a technological project, loaded with issues that are largely beyond the sole objectives of watching the planet for ecological aims, and it is a potentially federating project for a true European identity.