The international security literature has recently observed the growing “securitization” of issues outside the traditional concern with interstate military conflict. However, this literature offers only limited explanations of this tendency and largely neglects to explain how the new security issues are actually governed in practice, despite apparent “securitization” leading to divergent outcomes across time and space. We argue that the rise of non-traditional security should be conceptualized not simply as the discursive identification of new threats but as part of a deep-seated historical transformation in the scale of state institutions and activities, notably the rise of regulatory forms of statehood and the relativization of scales of governance. The most salient feature of the politics of non-traditional security lies in key actors’ efforts to rescale the governance of particular issues from the national level to a variety of new spatial and territorial arenas and, in so doing, transform state apparatuses. The governance that actually emerges in practice can be understood as an outcome of conflicts between these actors and those resisting their rescaling attempts. The argument is illustrated with a case study of environmental security governance in Southeast Asia.