The book examines the connections between energy, the environment, climate change and security from a military perspective and in the context of ongoing international conflicts. Adrien Esteve compares the cases of France and the United States, two nuclear powers and two of the largest militaries in the world, to understand the security aspects of global ecological upheavals and the energy transition.Drawing on insights from political science, international relations, history and philosophy, Esteve puts forward an innovative historical perspective on the environmental practices and discourses of the military. Chapters explore how, over the last decades, the civilian and military heads of defense organizations have been issuing a series of statements calling for armed forces to take greater account of environmental issues. He discusses this in light of the repeated denunciations of the ecological footprint of military activities and the environmental consequences of armed conflicts, revealing how the environment and climate change have been problematized within the defence sector.This book is an essential resource for students and scholars of international relations, security studies, environmental studies and political science. It is also an important read for journalists, activists and policymakers interested in the environmental cost of war and the militarization of the environment.