Considered as a human activity, war has always had a strong influence on the natural environment. Since the Vietnam War, the United Nations has issued many international reports, which have documented the ecological impact of warfare, and described the harmful consequences of some weapons (chemical such as agent orange, nuclear,…). Contemporarily, many international treaties and conventions have attempted to provide legal norms which prohibit the use of such weapons and other environmental modification techniques. But few works have actually tried to include environmental considerations in the field of war ethics, and build normative claims on this matter. In this paper, I will argue that the just war tradition provides a strong theoretical framework to address the environmental impact of warfare. This implies to rely on the three dimensions of this tradition and their criteria: jus ad bellum (moral criteria to start a war), jus in bello (moral criteria that need to be respected during the war), and jus post bellum (moral criteria regarding what happens after the war). First, we could use jus ad bellum to deal with what should be done before the war in order to prevent potentially harmful behaviors and certain weapons. This implies to focus on two connected requirements: just cause and proportionality. A just cause to start a war from an environmental point of view would be linked with the intensity of the harm. For example, we could be in favor of a “green intervention” aimed at protecting the natural environment from ecocides, which are direct and substantial damages, such as deforestation or deliberate heavy metal pollution. Two jus in bello criteria could also be used: discrimination and proportionality. Discrimination implies to make a distinction between combatants and non-combatants, and protect civilians from harm. The protection of natural elements, having both an intrinsic (as a natural being) and derivative value (as being essential to the living conditions of non combatants, to their human security), could then be justified. Proportionality would mean that, if there is a destruction of natural elements, it must be justified by a legitimate military objective. Finally, jus post bellum opens the door to reparations and compensations for the destruction of natural elements and resources. As far as environmental damages are concerned, we claim that reparations and compensations should be included in war ethics, considering their durable and sometimes countless effects.
