Security actors are important actors in the international community’s efforts to support peace in fragile contexts. Their activities affect not only the immediate security conditions in fragile contexts, but also the conditions for humanitarian assistance, development co-operation and peacebuilding. This paper explores the relationship between security actors and the broader international community in fragile contexts. It argues that security actors are needed to build peace in many fragile contexts, but that they can only contribute to peace where their activities are coherent with and complemented by appropriate civilian engagement. In doing so, it assists Development Assistance Committee members in their efforts to operationalise the Humanitarian-Development-Peace Nexus and to step up efforts to prevent conflict and build peace in fragile contexts. The paper is one of ten working papers supporting States of Fragility 2020 and together with Diplomacy and peace in fragile contexts, Conflict prevention in fragile contexts, and Peacebuilding in fragile contexts provides comprehensive background to Chapter 2 on peace in States of Fragility 2020.