In Europe and to a lesser extent in the rest of the world, the last decades have been characterized by two concomitant phenomena : the increasing cost of armament technology which has become always more sophisticated as well as the reduction in the strength of national armed forces and in their budget. In that context of restrictions, the implementation of armament programs in a strictly national framework appears to be more and more problematic. Resorting to co-operation and harmonizing the needs of the different armed forces turns out to be a "pressing necessity" or at least a pragmatic solution to many recurring difficulties.