At the end of the Cold War, the US Navy’s strategy and force structure were primarily directed at fighting a conventional enemy on the high seas. With the fall of the Soviet Union, the relative certainty of the Cold War was replaced by uncertainty about the challenges of the future. A number of threats, such as regional rivalry, terrorism, transnational crime, nationalism, and ethnic and religious conflicts, rose to prominence during the 1990s, replacing the Soviet Union as the main concern. This issue of IFS Insight investigates the Navy’s strategic ideas after 1989 by addressing change and con­tinuity in the blue water/littoral approaches to sea power in the US Navy. The blue water/littoral priorities of the Navy in this period will be illustrated by the Navy’s threat perceptions, the geographical and opera­tional focus of contemporary strategy documents, as well as the force structure and budgets.