Since the late 1990s, the sociology of IR has become a vibrant sub-field. Yet, despite its increasing popularity and sophistication, sociologists of IR have spent more attention understanding how knowledge is made in IR rather than what this knowledge does to international politics. Beaulieu-Brossard reconcile the former with the latter as implied in Bourdieu¿s thinking on reflexivity, drawing on Wittgenstein and Foucault¿s insights into the relationship between scientific discourse, power and governance. The book shows the impact of social scientific knowledge producers by analysing the influence of IR in the Iranian nuclear crisis from the American and Russian perspectives between 1998 and 2016. Concrete practical examples reveal how IR often provided symbolic and/or instrumental knowledge sustaining the crisis at one time, and resolving it at others. This book will be of interest to a wide audience of academics, think tank experts, policy-makers and students concerned about the role of knowledge in the politics of security.