Decision support systems (DSS) are computerized tools that are designed to aid such human decision-making. They do so by displaying, synthesizing or analysing relevant information, and/or by proposing options for how to achieve a goal. Even though DSS do not “make” decisions, they directly and often significantly influence the decisions of human decision makers. As a result of advances in areas like computing, artificial intelligence (AI) – especially machine learning – data collection and communications, their capabilities will grow significantly in the years ahead, as will their influence on military decision-making. This report is intended to illuminate the functions of military DSS – in particular, increasingly machine learning-based DSS – and highlight their implications and some key limitations that could be relevant for the application of the law to human decisions in the process leading to the use of force.