As climate change is at the top of the world’s agenda, the armed forces and other defense actors must give a signal that they are environmentally responsible. In this regard, the defense industry should be one of the first actors to devise new strategies and actions aimed at reducing the environmental footprint. This article focuses on the measures being taken by the defense industry and the armed forces, and on how technology, the circular economy (CE) and Lean principles can contribute to a better environment. A qualitative multimethod research model was used, covering more than one research method, such as a systematic literature review and a case study research. Although the literature highlights that the defense sector in Europe is far from being a green actor, a transition to the CE was identified. In that regard, the European Union (EU) defense industry has been a key player in CE R strategies, such as: repurpose, remanufacture, repair, reuse, reduce and rethink. The contribution of new technologies has empowered military equipment to acquire enhanced characteristics, such as material resistance, while EU technology centers have been instrumental in a green transition. Additionally, more comprehensive research is needed in order to allow generalization of the results.