Preventing accidents within a complex environment like a force on force military exercise ischallenging for the organization. The aim of this study is to investigate safety behavior by usingactivity theory in combination with critical incident technique in order to identify conditions effectingthe health and safety of individuals employed by the Swedish armed forces (SwAF) participating inmilitary exercises. The empirical data was collected from two separate events final planningconference of Northern Wind 2019 (FPC-NW19) and the exercise Northern Wind 2019 (NW19). Datawas collected using observations and conversations with military, medical and safety professionals.One researcher followed the FPC-NW19 and the observed the exercise NW19 by shadowing staffmembers and safety personnel.Data was analyzed, thematized and coded using the third generation of activity theory and its areas:tools, rules, community, division of labor, subject and object as a guide for identifying contradictions.Results indicate that the methods used for planning and the use of safety equipment whenconducting military tasks during the exercise is influenced by the desire of winning the exercise.The results also indicate that activity theory can be a useful tool to identify contradictions affectingsafety performance. However, the study is only limited to two events with a narrow scope from theArmy. Further refinement is needed to develop a functioning method for analyzing safety behavior.