Abstract
Why and how do states decide to develop different weapon systems within a similar domain of warfare? For example, why does the United States invest in ever-more expansive forms of national missile defense, while France briefly dabbled in such matters and the United Kingdom has been reluctant to do so? Contrary to the assumption in the existing literature that states know the future threat environment and are able to develop suitable military technology in response to it, I argue that ideas, particularly those about the future, play a critical role in shaping states' decisions about military technology. Because the future is unknown, domestic actors imagine radically different future states of the world. These ideas—what I call “images of warfare,” consisting of actors' construction of future threat environment and their theory of victory—shape actors' preferences for weapons systems. Not all of these ideas, however, are equally influential. In order to transform their ideas into actual capabilities, actors need to build cross-cutting coalitions within the broader defense community around their “imagined security interests.” The ability of these actors to build such a coalition and funnel their ideas through the state's decision-making process is shaped by the political opportunity structure, more specifically the level of openness of the relevant institutions. I explore these dynamics through an in-depth case study of the development of missile defense capabilities in the United States from the 1980s until the mid-1990s.