The Bush administration's invasion of Afghanistan in response to 9/11 has been widely seen as a simple and understandable act of self-defense. This impressive study, however, sees it as part of a deeper recurring drama in world politics: that of major states struggling to defend sovereignty and great-power authority from violent transnational threats that endanger not just lives but also the norms of order. Löwenheim notes that throughout the modern era, powerful states have been menaced by "persistent agents of transnational harm" -- pirates, drug cartels, terrorist networks -- but the responses to these threats have varied. Leading states are most likely to act aggressively against these nonstate outlaws when they challenge the foundations of great-power rule. Thus, sixteenth-century Spain's toleration of piracy and the nineteenth-century United Kingdom's aggressive enforcement of maritime law are explained by the evolving norms of order: and so the differences in the United States' responses to the 1980s terrorist attacks in Lebanon and to 9/11. To be sure, the 2001 attacks were more violent and hit the U.S. homeland, but Löwenheim contends that it was al Qaeda's challenge to the institutions of great-power authority and U.S. dominance of this system of global rule that made the response so determined and aggressive. Punishment is not just about attacking threats but also about reaffirming the "moral order" of the system.