 The role of external actors in peace building and post-conflict state building has been a subject of much debate. How effective is the current international peace building architecture? How can development policy be better used to help countries recovering from wars? The United Nations has been one of the major organisations to have peace operation around the world. The role is to try either to stop a conflict or to maintain a ceasefire. You need large deployment of troops in different locations of the country with a mandate to actually not just observe but also be able to enforce the resolution of the United Nations. In the public discourse the United Nations in terms of peace operation seems a waste of money, seems that are ineffective. Actually UN peace operation are cost effective and they stop the fighting. The lessons on sustainable peace actually are harder because one thing is to stop the fighting, the other thing is building the peace in a long lasting way. Countries emerging from conflict need aid, they need technical support, they need knowledge but ultimately is about understanding what the citizens of the countries want, are willing to fight for and need and sometimes those wishes are not aligned with external views or the aims and purposes of international donors and international assistants. We can't just think of putting institutions in place, expecting them to work in the same way in every context. We need to craft the institutions to fit the cultural context. There is a role for external intervention but that role is to support autonomous state building and internal processes rather than impose views that may not matter for people that at the end of the day are just trying to survive and rebuild their countries.