"In remarking that 'war is merely the continuation of policy by other means,' Clausewitz unambiguously defined the conduct of war--the use of military force--as a means for a state to achieve policy and not an end in itself. He implied, but did not state, that other means must also exist. These other means as well as the use of military force emanate from the four elements of national power: military, economic, political, and social. What Clausewitz did not discuss in his treatise On War were the circumstances under which war becomes the correct means with which to pursue policy--the imposition or dominance of one state's national interests over those of another state. He never answered the question: When is it proper to use military force in the pursuit of national interests?" This article explores the answer to that question.
U.S. Army War College, Parameters: http://www.carlisle.army.mil/usawc/parameters/
Parameters: United States Army War College Quarterly (Spring 1994), v.24, p.4-12