To what extent can the environment be used as a weapon of war by belligerents? How can the impact of conflicts on the environment be measured? In this new episode, Mathilde Jourde, Co-Director of the Defence and Climate Observatory and Head of the “Climate, Environment and Security” Programme at IRIS, speaks with François Grünewald, President and Founder of Groupe URD (Urgence – Réhabilitation – Développement), who has been studying the environmental footprint of conflicts around the world for more than thirty years. Since the Russian invasion of Ukraine in February 2022, he has carried out numerous field missions to assess the direct and indirect impacts of the fighting on ecosystems. These effects, varied and profound, stem both from collateral damage linked to military operations and from the deliberate use of the environment as an instrument of war. François Grünewald also reflects on the influence of climate change on combat zones and on the environmental challenges associated with the country’s future reconstruction. Finally, in view of the scale of the destruction observed, he questions whether certain acts could be characterised as environmental crimes amounting to war crimes in the context of Russia’s aggression against Ukraine.