This chapter discusses the conceptual contestations around the border/security nexus within the context of the renewed nationalism and authoritarian politics in many parts of Europe, the United States and beyond. It asks how critical scholarly discussions on borders are changing in light of these political trends. The argument covers three distinct lines of contestation in the literature on borders and security. The first one centers on sovereignty and its contemporary modalities. The second one concerns security and the practices it underwrites. The third one focuses on risk, and its relative merits as a measure informing border policy. The chapter argues that technocratic securitization contributed to a relative depoliticization of borders over the course of the past twenty years. As contemporary claims to specifically national sovereignty increasingly animate events at borders, research and scholarship must regard borders anew as above all a political stage.