That problem is in all likelihood a byproduct of the paucity of serious research on the subject of fortification in recent years. (An examination of Parameters' index of books reviewed between 1996 and 2010, for instance, shows only one dealing with the topic, Breaching the Fortress Wall, a RAND Corporation monograph from 2007 focused on the vulnerability of modern infrastructure to terrorism.) By and large, the available literature examines particular defensive works, conflicts, or periods (for instance, Medieval castles or Civil War forts), or is part of broader histories of wars and warfare (such as John Keegan's 1992 A History of Warfare, which Sterling cites three times in his discussion of basics in his first chapter—a reliance that is telling).
Naturally, serious book-length studies offering cross-cultural comparisons, or dealing specifically with strategic barriers as a class, are even rarer than writing on fortification in general, which is by itself enough to make Sterling's book worthy of attention. The interest of the book is reinforced by its particular approach to the subject matter, emphasizing the effect of such defenses on the behavior of major actors involved by way of three central questions: first, how the barrier affects "adversary perceptions of