The paper examines the political significance and interest of resorts to the precautionary principle. The precautionary principle may in fact be invoked by the decision theory in the realm of security, in particular on an international level. How should we face the increasing risks stemming from modern figures of conflicts? Such an increase in risks encourages a growing technologization and globalization of security devices. The uncertainty that pertains to such an evolution of risks points nevertheless to the responsibility of decisionmakers, whose ethical duty lies in a resort to the precautionary principle as a guide towards the future, not only in the field of environment or health, but also in the realm of public security.