Despite staggering defense costs, the U.S. military has not learned how to confront terrorist and insurgent networks. Traditional thinking and special interests have concentrated on potentially outdated systems, like aircraft carriers and heavily armored vehicles. Our ability to wage irregular warfare against networked forces has been stunted. Meanwhile other nations have innovated and developed techniques that will surpass the capabilities of the hidebound American armed forces.... Worst Enemy offers an inside analysis of the events that have derailed our efforts to transform the nation's military into a leaner, lighter, and much more "networked" force. Mr. Arquilla places these events in historical context and assesses Donald Rumsfeld's role as secretary of defense of the post-9/11 era.