This research explores the intersection between circular economy strategies, critical raw materials (CRMs) and the defence sector, especially focusing on Neodymium-Iron-Boron (NdFeB) magnets. The significance of CRMs in modern defence applications and the associated risks of geopolitical and supply chain disruptions underscore the necessity for a secure supply. Circular strategies are crucial not only for securing a stable supply of CRMs but also for their potential to significantly reduce environmental impacts. This study aims to determine the effectiveness of various circular strategies in securing a stable supply of CRMs, thereby enhancing national security and promoting environmental sustainability. To address the research question, a mixed-methods approach was employed. Secondary data collection involved a review of scientific and grey literature, while primary data was obtained through interviews with experts. The conceptual framework was based on the 9R framework of circular strategies, chosen for its comprehensive coverage of all value retention options, from smarter product use and manufacturing, and lifespan-extending practices to the useful application of materials. This framework was adapted to the context of CRMs. The analysis was conducted using the backcasting method to develop strategic pathways for implementation. From the results, it is clear that NdFeB magnets are crucial to the defence sector due to their exceptional magnetic properties. This makes them indispensable in various defence applications, such as in motors, sensors, and communication devices. The reliance on CRMs like neodymium and dysprosium for the production of NdFeB magnets poses a significant risk due to their limited supply and geopolitical concentration. The study identified effective circular strategies on all 10 levels of value retention. This includes modular design, which facilitates easier disassembly and reuse, and advanced recycling techniques like hydrogen decrepitation, which efficiently reclaims materials. These strategies are already being implemented in the civil sector and can be adapted for defence applications to enhance sustainability and resource efficiency. To implement the circular strategies in the defence sector, barriers and enablers are highlighted on four levels: cultural, regulatory, market and technological challenges. Culturally, the defence sector has a somewhat conservative approach in which operational effectiveness is considered most important. Awareness about sustainability and CRMs can be created through programs, training and role modelling. Secondly, the defence sector is heavily regulated with stringent standards for performance and safety. Therefore, policies are important to ensure that circular practices comply with existing standards and incentives should be created. On the market level, commercial considerations are said to be the hardest challenges which should be taken care of in procurement processes. Lastly, adopting circular strategies involves technological innovations for which investments and development are crucial. Collaboration among various stakeholders is essential to the implementation. A detailed implementation plan is provided including measures to overcome the barriers alongside an indication of time. The research concludes that implementing circular strategies on NdFeB magnets within the defence should be improved as many more benefits can be gained from further implementation especially with regards to lowering dependence on CRMs. By adopting these strategies, the defence sector can not only secure a more reliable supply of critical materials but also contribute to broader sustainability goals. The circular strategies could be tailored to fit specifically into the defence sector by addressing unique challenges and leveraging opportunities.