Section IX of the ICRC Interpretive Guidance on Direct Participation in Hostilities asserts: ‘In addition to the restraints imposed by international humanitarian law on specific means and methods of warfare, and without prejudice to further restrictions that may arise under other applicable branches of international law, the kind and degree of force which is permissible against persons not entitled to protection against direct attack must not exceed what is actually necessary to accomplish a legitimate military purpose in the prevailing circumstances’. The present article scrutinises arguments that have been, or can be, advanced in favour of and against a ‘least harmful means’ requirement for the use of force in situations of armed conflict as suggested in Section IX. The principal aim of the article is to examine the question whether such an additional proportionality requirement forms part of the applicable international lex lata.
