Although students of Raymond Aron’s Peace and War might rightly bemoan the fact that this book has had relatively little impact on Anglo-American scholarship, the question arises as to whether Aron has anything significant to teach us today. After all, Aron is often seen first and foremost as a Cold War theoretician: is he the best person to turn to in order to make sense of events like Islamic fundamentalism, global terrorism, and the apparent importance of transnational organizations and treaties, to name just a few pertinent issues? This article hopes to demonstrate that Aron’s theoretical framework serves as a very useful starting point in conceptualizing international politics—including current politics—in a most comprehensive fashion. The article sketches Aron’s distinctive moral contributions to international relations theory and suggests that his conceptual framework can help us to understand, both theoretically and practically, the threat posed by Islamic fundamentalism and terrorism.