System dynamics in defence analysis: some case studies

System dynamics has proved to be an effective and efficient methodology for the analysis of defence problems. The paper first reviews some academic background to the defence applications of system dynamics, that is followed by a brief account of two case studies which illustrate the very wide variety of problems in this domain. Not only are the problems different but their analysis illustrates two aspects of system dynamics. Firstly its role is traditional quantitative modelling but it is shown that this is enhanced when system dynamics is combined with other methodologies, and secondly it shows system dynamics' scope for shedding light by purely qualitative, diagrammatic, analysis. However, defence is not solely a matter of the conduct of military operations of different types but also includes the special problems of finance and procurement. Work in that area is dealt with by a brief account of two applications. Finally, the reasons for the success of system dynamics in this domain are considered.