means and methods of warfare
141
present and those of the future’.108 The International Group of Experts adopted the same approach by concluding that the general rules that determine the legality of weapons will also determine the lawfulness of cyber methods and means of warfare. 2. The Rules set out in this section apply in relation to methods and means of warfare that a State develops or procures for use by its own armed forces. Moreover, they apply to any means of warfare over which a State acquires control. A State that acquires control by cyber means over enemy weapons is subject to the law of armed conflict applicable to those weapons. Consider the case of an Unmanned Combat Aerial System (UCAS) armed with cluster munitions. If the State that acquires control over this system is a Party to the Cluster Munitions Convention,109 it would be prohibited from using the UCAS to deliver such weapons. The notion of acquiring control implies that the Party using cyber means exercises sufficient control over the system to employ it as if it were its own. This situation must be distinguished from one in which cyber means are used to attack, neutralize, or otherwise interfere with enemy systems, as in the case of taking control of an enemy UCAS in order to cause it to crash.
Rule 41 – Definitions of means and methods of warfare For the purposes of this Manual: (a) ‘means of cyber warfare’ are cyber weapons and their associated cyber systems; and (b) ‘methods of cyber warfare’ are the cyber tactics, techniques, and procedures by which hostilities are conducted. 1. The terms ‘means’ and ‘methods’ of warfare are legal terms of art used in the law of armed conflict. They should not be confused with the broader, non-legal term ‘cyber operation’ used throughout this Manual. Cyber operation simply denotes a particular cyber activity. The definitions set forth in this Rule are applicable in both international and non-international armed conflict. 2. For the purposes of this Manual, cyber weapons are cyber means of warfare that are by design, use, or intended use capable of causing either (i) injury to, or death of, persons; or (ii) damage to, or destruction 108 109
Nuclear Weapons Advisory Opinion, para. 86. Convention on Cluster Munitions, 3 December 2008, 48 International Legal Materials 357 (2009).