The study of emotions in International Relations is gaining wide-spread attention. Existing approaches have not given sufficient recognition to psychological motivation, and instead focused on rational actor model explanations concerning human aggression. This book explores the emotion of rage through an innovative approach that seeks to split rage into its violent manifestation of aggression and revolt, and into a less visible, passive manifestation of brooding resentment. This model facilitates a comprehensive understanding of revisionist motivation, from the violence of ISIS to the brooding resentment of Putin's Russia. The aim is to illustrate how even a lack of visible violence can belie vengeful impulses that might explode at any moment, and how any act of violence, regardless of brutality, is framed as a type of justice and good in the mind of the aggressor. This book raises serious questions and concerns about legitimacy and order in global affairs, and offers a firm theoretical basis for the exploration of present day conflicts. This work will be of great interest to students and scholars of international relations, IR theory and conflict studies.