The thesis is a discourse analysis of the United States decision to go to war against Iraq in 2003. What traditions and arguments could defend or legitimize a unilateralist intervention, which was opposed by so many of the United States traditionally close allies? The thesis assumes that to understand this decision, one must look at the inside of the U.S. foreign policy discourse. The domestic interpretation and framing of the September 11 attack is essential to the decision about intervention, it is argued. U.S. foreign policy is shaped by at least four internal factors at the domestic level. These internal factors, or main dimensions, of U.S. foreign policy, are American exceptionalism, popular sovereignty, unilateralism multilateralism, and homeland security. The overall aim of the thesis is to explore how these four main dimensions of U.S. foreign policy discourse enabled the decision to go to war against Iraq.