It is widely argued that the first applications of operations research date back to World War II where the contributions of scientists included the establishment and application of scientific methods for solving of military problems. Operations Research (or Operations Analysis) has been part of the military domain ever since. This session addresses the application and impact of operations research on the defence sector in recent time, and the applicability of operations research to the future of defence and national security. Papers in this session include the application of techniques to specific defence problems through to the combination of multiple techniques to address some of the wider more philosophical defence questions of today.