As no biological organism can efficiently pursue its needs and continue its survival denying the habitat that it lives in, the states will find it extremely hard to survive in the international environment by disregarding the constraints and opportunities presented by the structure of the international system. Furthermore, it would not be entirely correct to say that the agents always exactly and entirely understand their environment. The decision maker perceives the structure in a certain way. Harold and Margret Sprout call this subjective view of the environment as the “psychological milieu”, while the actual environment in which the policy will be carried out is called the “operational milieu”.