"National interest lies at the very heart of the military and diplomatic professions and leads to the formulation of a national strategy and the calculation of the power necessary to support that strategy. Upon reflection, however, one comes to realize how hard it is to turn concepts of national interest into working strategy. It requires one to perceive the world with undistorted clarity and even to anticipate the second- and third-order effects of policies. This essay will argue that the concept of national interest still has utility, not as an objective fact but as a philosophical argument in favor of limiting the number of crusades a country may be inclined to undertake."
U.S. Army War College, Parameters: http://www.carlisle.army.mil/usawc/parameters/
Parameters: United States Army War College Quarterly (Winter 1994-95), v.24, p. 4-18