In recent decades, not only peace but also security has become a ‘contested’ concept. The military-focused and state-centred reading of traditional strategic studies has been put on the defence. The expansion of the research agenda by new security sectors – economic, environmental, cultural – and new security referents – societies, non-state actors, individuals – is challenging the ‘realism’ of the strategic gaze that has for so long dominated the field. This conceptual widening has led to an erosion of the walls that previously divided strategic studies and peace research. To some extent, the two fields have merged to become security studies, which covers a range from more traditional approaches (Walt 1991) to so-called ‘critical security studies’ (Krause and Williams 1997).