4 Domains of Warfare
This chapter examines ‘domains’ of warfare, which are generally understood as the operational environments in which armed conflict occurs, and to which international humanitarian law (IHL) therefore applies. Until recent decades, domains of armed conflict have been largely predicated on geospatial conceptions, denoting the physical places where armed conflict has customarily occurred: land, sea, and air. General IHL applies across all these areas—including the fundamental principles of humanity, military necessity, and proportionality; restrictions or prohibitions of certain means and methods of warfare; and basic rules requiring humane treatment of persons and respect for civilians and civilian property. Over time, however, the particular exigencies of land, sea, and air warfare have led to the development of some specific IHL rules and principles tailored to each of those environments. Discussing domains of armed conflict therefore offers a window into the historical development of IHL. It shows how the emergence of new operational environments and new means and methods of armed conflict catalyses efforts at legal regulation, which can lead to the development of new domains or sub-sets of IHL. The chapter then considers how the idea of a domain might apply to armed conflict in outer space, and armed conflict involving cyber operations and other emerging capabilities.