This article argues that there are two barriers to operationalising the Women Peace and Security resolutions at the mission level that deserve further attention. The first barrier is that the legal architecture has flaws, and does not seem to be matched with a commensurate political commitment that shapes the high-level UN response at the level of mandate. The second barrier relates to the institutional ability to deliver a peacekeeping mission with gender equality at its heart, related to the capacity of domestic militaries. The article argues that there needs to be deeper thinking about the capabilities of modern militaries to fulfil complex peace operations which contain the imperative for gender sensitive for conflict analysis, planning, security sector reform, disarmament, DDR, and disaster response. The slow progress of gender reform of militaries is hindering credible regulatory responses in UN missions. The article concludes that this creates lingering distrust of military intervention as a tool to protect women and girls, even from conflict-related sexual violence, even in a peace-keeping context.