Existing research shows that peace after civil wars is more stable with peacekeepers present. Yet, violence persists in many postwar contexts, and although postwar violence is often strategic and closely linked to the faultlines of the preceding war, we know little about the impact of peacekeepers on such violence. What we know, moreover, focuses on the former combatants, while this study shows that the majority of deaths in postwar violence are inflicted by other armed actors. This is a challenge for peacekeepers who – for mandate or capacity reasons – usually focus on the warring parties. I argue that the impact of peacekeepers on postwar violence hinges on the extent to which they fill a public security gap after war, since responsibility for violence not covered by a mission’s mandate lies with the often dysfunctional security agencies of the state. To test this I use a novel spatial approach to generate data that captures the manifold manifestations of violence across different postwar contexts. I find that only UN police – with their broader effect on public security – mitigate postwar violence generally. UN troops have some impact on civilian targeting by former combatants but no such effect could be identified for violence by other armed actors. The findings highlight the importance of peacekeeping police at a time when the modus operandi and capacity of UN police have been questioned, but also the importance of accounting for a multitude of violent actors when analysing the impact of international interventions more generally.