"Any individual, group of people, institution, organization or State who or which, from various motives (religious, moral, politico-economic, etc.), exerts an intentional effect, directly or not, on political, economical, military, social and other systems in order to reinforce, restrict, modify or compensate for them."
(Dobenik, R. V., dir., Dictionary of International and Strategic Relations, Paris: Ellipses, 2007)