I owe many thanks for help in the writing of this book to two anonymous reviewers of the manuscript for Johns Hopkins University Press, to all the people who got trapped into substantive discussions when they simply asked the innocent question “What are you working on now?” and especially to a long series of colleagues and other seminar participants at the University of Maryland and at two dozen other universities and research centers. Todd Lowery and Gil Peleg were very helpful as research assistants. The book is an expansion and major revision of an exploratory study done with support from the Office of Net Assessment in the United States Department of Defense. The completion of the book, entailing a trying-out of the arguments in seminars around the United States and at a series of international security-oriented institutes around the globe, was facilitated by a grant from the Smith Richardson Foundation. Neither of these organizations is, of course, in any way responsible for the views expressed in this book. A version of Chapter 1 was published in the Spring 2005 issue of Naval War College Review.