This thesis examines the methods through which the administration of George W. Bush utilized the events surrounding the attacks of September 11, 2001 (9/11) to legitimize a type of imperial American foreign policy. The central argument of this research is that 9/11 was used by the Bush administration to present a perceived shift in the danger and threat that America faced, thus legitimating a more aggressive foreign policy, which this thesis categorizes as ‘informal imperialism’. It argues that an American grand strategy of global dominance is not new, but rather constitutes a continuation of policies whose ideological roots date back to the 1990s. This thesis explores this argument through the lens of critical geopolitics (CGP), which provides a critical and interdisciplinary framework for unpacking geographical assumptions in geopolitics and questions how they function within ideology. CGP serves as a framework for understanding the use of language in constructing and normalizing imperial policies in the United States after 9/11. Methodologically, this thesis used critical discourse analysis (CDA), which provides tools for analyzing discourse, and examining how language is the key to understanding how power functions. This thesis deploys a critical analysis and definition of American imperialism and the contributions of CGP to the debate of a ‘post 9/11 world’. A CDA of the writings of key people in the Bush administration traces their foreign policy and its ideological roots. Further, a CDA of post 9/11 discourses focuses on the changing geography of danger, fear, threat and the act of Othering as it relates to a post 9/11 world. Finally, a CDA of the discourses surrounding the Global War on Terror is conducted, arguing that the frames set up in relation to a new and dangerous world paved the way for policies that justified a war with Iraq.