The defence sector is critical for maintaining the safety and stability of our society. However, the sector is at risk from climate change either through direct impacts of climatic hazards or indirectly because of its dependence on vulnerable entities that operate critical energy infrastructure. The defence sector must therefore increase its resilience to climate change. A new study of the European Commission’s Joint Research Centre and the European Defence Agency addresses for the first time the climate-energy-defence nexus and proposes actions for EU defence to ensure climate resilience and energy sustainability.