By what legal and security narratives have the United States, France and Britain justified their « war on terror » lethal security policies since the
early 2000? During the period from the 1970s to the 1990s, the United States and its allies were reluctant to assume that their armed forces were carrying
out lethal actions. This situation, stemming in part from criticism of the colonial and Vietnam wars, lead the armed forces to be less reliant on the use
force (as was the case during peacekeeping operations in the 1990s) or to hide their violence (referred to as « zero casualties warfare » or « surgical
warfare »). After September 11th, 2001, a change occurred; political and military decision-makers are  much more willing to acknowledge the fact that
their armed forces are causing death. Based on both critical legal studies and critical security studies approaches, this project aims at enquiring how the
mortality – affecting individuals labelled as « terrorists » but also numerous civilians, resulting from actions taken in the context of the « war
on terror »  - has been justified by legal and security discourses. It hypothesizes that this change was justified by five narratives : (1) traditional
international law, which limits the use of force, as an « obsolete » frame; (2) targeted killing as an expression of a « utilitarian strategic
calculation » supporting a « preventive » conception of armed actions ; (3) large-scale military operations (in particular within cities) as a means of
« liberating populations taken hostage » ; (4) support for militias as a means of « strengthening sovereignty »; (5) lethal effects on civilian
populations of arms deliveries as « unproven ».