Michael Walzer’s work is one of the keys to understanding the resurgence of the Just War that could be seen in the 90s. The foreword, through the example of the Gulf War, illustrates how political or military decisions lead to armed conflict are a major moral problem that has an impact on the combatants themselves, as well as on the civilian population and on which discussion is needed. Walzer raises topical issues such as the issue of pacifism and its consequences, the need to distinguish and justify the right to war or the right in war and to show that only the existence of a regulatory regulation on the Just War will achieve the objective of ceasing to be an unlimited resource.