The nature of wars has changed in the last century, evolving from classical wars between states to revolutionary wars, national liberation wars or cold war conflicts. A fifth type of conflict has widely taken over all its predecessors: the 'new wars'? - in fact civil wars - oppose two or more parties fighting on a single territory, with possible regional repercussions. This article explores the causes and consequences of these conflicts and examines the answers brought by the international community. This type of conflict has mostly taken place on the African continent but the Asian and American continents have not avoided it either (e.g. Sri Lanka, Philippines, Nepal, Myanmar, Colombia, Salvador, Nicaragua, Guatemala).