This book critiques the conceptualisation of security found in mainstream and critical theoretical debates, and applies this to the empirical case of the 2003 Iraq War. Responding to constructivist and poststructuralist scholars' calls for a turn to discourse, and aligning its argument with critical security studies, particularly the Copenhagen School (CS), the book conceptualises language as a pivotal mechanism of power. However, the argument developed here seeks to move beyond securitization by reconceptualising the language of security not so much as a speech act or utterance, but as part of an on-going process or language game. Adopting a Wittgensteinian approach, it moves away from thinking about the nexus between security and language from a single action, or speech act, to a series of actions or interactions. Thinking about language as a process allows us to move beyond the dominant conceptualisation of rules, i.e. rule breaking, found within securitization. The Bush administration's justifications for the 2003 Iraq war are taken as a third avenue to show that how security is 'spoken' matters. The narratives they constructed to justify the 'pre-emptive use of force' and 'enhanced interrogation techniques' consolidate the book's argument that adjustments are needed in the way security is currently spoken in theory and practice. To explore and substantiate this claim, the author examines two 'defining moments' that occurred during their securitizing move to invade Iraq in March 2003. The first is after the UN inspectors' finding that there was no credible evidence that Iraq possessed WMD in early 2003; the second is the Abu Ghraib scandal in April 2004. Both represent periods of acute crisis, which forced the Bush administration to define and redefine what they deemed legitimate in the name of security. Paradoxically their use of the language of security turned into a security problem. Although the two cases yield different results in constraining the Bush administration's ability to speak security in a meaningful way, they both illustrate a more general po∫ that the boundaries and relations between securitized rules and environments are not pre-given but produced in a particular language game. In sum, this book makes a new contribution to the development of scholarship investigating the role of securitized rules in world politics. This book will be of much interest to students of critical security studies, US foreign policy, and IR in general.