The world forever changed the morning of September 11th, 2001. The attacks on the World Center represented the most serious terrorist acts ever carried out on US soil. A watershed moment in world history, that fateful morning will forever be engrained in the American national psyche. From a political, social, and economic perspective, the hijackings of 9/11 were unparalleled in scope and sheer devastation. In a fascinating article entitled “Measuring the Effects of the September 11 Attack on New York City”, it was estimated that the direct cost of the attack stood at between $33 billion and $36 billion to the city of New York (Orr, Bram Rappaport 55). In addition to the direct economic costs associated with terrorism and the threat of further terrorism, 9/11 also had important political ramifications.Importantly, political scientists have been wracking their brains trying to make sense of the horrific violence undertaken the morning of 9/11 and further violence inspired by global jihadists bent on taking over the world. Psychologists sought to explore the psychological factors leading people to kill in the name of Allah, domestic-level theorists explored the domestic antecedents to terror including extreme poverty, a lack of education, and political repression. System-level theorists, however, were at a loss to explain the attacks of September 11th and the ensuing War on Terror. Although realism will have to evolve to take into consideration the changing face of the international order, particularly in light of the emergence of sub-state actors who wish to fundamentally destroy this present international order, realism is the best system-level theory to understand the global War on Terror.Realism, as an explanatory theory of international relations, provides perhaps the most concise and strongest definition of what constitutes state interest, behavior, and the establishment of the international order. Accordingly, realists argue that states exist within an anarchic geopolitical framework and this framework is an inherent component of international relations.