LOIAC affords special protection to certain categories of persons, ‘either because they are regarded as especially vulnerable or on account of the functions they perform’.1229 Those specially protected include both combatants and civilians. Combatants endowed with special protection gain, above all, immunity from attack. With civilians, the position is different. All civilians (not directly participating in hostilities; see supra 587 et seq.) are anyhow entitled to immunity from attack: when special protection is granted, some complementary measures of protection are envisioned. What needs to be underscored is that the addition of these forms of greater protection to selected subsets of civilians – e.g., women and children (see infra 672 et seq.) – does not detract from the general protection accorded to all civilians. Thus, the special protection of women and children does not diminish in any way the unlawfulness of an attack against male civilians in the prime of their lives.1230

It is prohibited to attack, destroy, remove or render useless objects indispensable to the survival of the civilian population, such as foodstuffs, agricultural areas for the production of foodstuffs, crops, livestock, drinking water installations and supplies and irrigation works, for the specific purpose of denying them for their sustenance value to the civilian population or to the adverse Party, whatever the motive, whether in order to starve out civilians, to cause them to move away, or for any other motive.

Law must not be confused with liturgy. It is not enough to enact and reiterate the law: to be meaningful, norms must be adhered to in reality. The nature of LOIAC is such that Belligerent Parties tend constantly to trade mutual accusations of breaches and worse. Absent effective modalities of supervision and dispute settlement, there is no way to guarantee a thorough implementation of LOIAC in violent clashes between States. No enforcement mechanism established thus far has been crowned with signal success. There is a growing acknowledgement of the need to prosecute and punish war criminals for serious breaches of LOIAC, especially since the establishment of the ICC. Yet, it is by no means certain that war crimes trials by themselves can put an end to LOIAC infractions. Debates about forging novel mechanisms, with a view to securing a more efficacious performance of LOIAC undertakings, are not likely to fade away in the foreseeable future.

The present book deals with the conduct of hostilities governed by the law of international armed conflict (LOIAC). The threshold of an international armed conflict (IAC) is crossed automatically once two or more States wage hostilities against each other, irrespective of the intensity or the length of the fighting.1 As the Appeals Chamber of the International Criminal Tribunal for the Former Yugoslavia (ICTY) pronounced in the Tadić case, ‘an armed conflict exists whenever there is resort to armed force between States’.2 Depending on their scale, IAC hostilities may make the grade of a full-fledged war or they may amount to a ‘short of war’ clash of arms (namely, constitute a mere incident), but either way the military engagement between two or more States invites the application of LOIAC.

The cardinal principle of distinction in LOIAC (supra 40–1) is of fundamental importance: it affects the entire normative architecture relating to susceptibility to attack in the course of hostilities by dividing the population of Belligerent Parties into two disparate categories of combatants and non-combatants. The goal of the bifurcation is to ensure in every feasible manner that IACs are waged among combatants while sparing non-combatants (primarily, innocent civilians). Of course, this goal is easier to verbalize than to apply in the intense strain of hostilities. In consequence, there are occasional scholarly attempts to expose ‘the ambiguity, instability and indeterminacy of distinction’.247 But, whatever challenges are encountered in the implementation of the principle of distinction, it cannot be denied that it constitutes a recurrent leitmotif of both customary and treaty LOIAC. The Security Council, too, has stressed the importance of ‘distinguishing between, on the one hand, civilian populations, civilian objects and all other persons and objects afforded protection, and, on the other hand, combatants and military objectives’.248

Cultural property and places of worship are paradigmatic civilian objects and, as such, must not be the targets of attack in warfare. Article 52(3) of AP/I (quoted supra 365) expressly refers to places of worship and schools as the prototypes of civilian objects. The clause creates a presumption that these objects serve their normal civilian purposes, but it takes into account the possibility that they will be subjected to military use. Should the normal-civilian presumption be rebutted, even schools and places of worship may become military objectives.

‘Weapons’ are means of warfare, including any arms (for instance, missile launchers, artillery, machine guns and rifles), munitions (for example, missiles, bombs, mines, shells and bullets) and other devices (including cyber malware) or mechanisms striving to (i) kill, disable or injure persons; or (ii) destroy or damage matériel or property.422 Weapons encompass also weapon systems (with diverse components or external delivery/guidance means) and platforms carrying weapons (such as tanks or warships). Military platforms not carrying weapons (e.g., troops-carrying trucks) do not qualify as weapons per se, even though they contribute to military operations.423 Generally speaking, weapons can be categorized in a binary fashion as (i) conventional weapons and (ii) weapons of mass destruction.

The history of LOIAC can be described as a sustained effort to ensure that innocent civilians are protected from the havocs of war. Notwithstanding LOIAC strictures, it is impossible to preclude altogether the possibility of civilian casualties and damage to civilian objects in wartime. Indeed, some civilian losses and damage are virtually postulated, as long as they constitute lawful collateral damage (see infra 505 et seq.). However, the obligation of Belligerent Parties to distinguish at all times between civilians and combatants – as well as between civilian objects and military objectives – is the mainspring of LOIAC as it currently stands and as reflected in the ‘[b]asic rule’ of Article 48 of AP/I (quoted supra 328). Allegations that ‘[t]he distinction between combatant and non-combatant has all but vanished’927 are utterly at odds with present-day LOIAC.

The importance of the natural environment is universally acknowledged. As the ICJ articulated the idea in its Advisory Opinion on Nuclear Weapons:

War crimes constitute breaches of LOIAC giving rise to penal accountability of the individuals who perpetrated the proscribed acts. In the past, it was frequently asserted that every breach of LOIAC was a war crime, but – as pointed out already by H. Lauterpacht – ‘textbook writers and, occasionally, military manuals and official pronouncements have erred on the side of comprehensiveness’ in making ‘no attempt to distinguish between violations of the rules of warfare and war crimes’.2179 It is currently clear that only select violations of LOIAC are stigmatized as war crimes.2180 Some of these violations are regarded as ‘grave’ breaches (see infra 1066). But ‘[o]ther serious violations’ of LOIAC are listed as war crimes in Article 8(2)(b) of the Rome Statute (see infra 1067). Of course, by itself, the adjective ‘serious’ (or, for that matter, ‘grave’) does not provide a useful compass indicating the contours of war crimes.2181 War crimes must be defined in specie.

The requirement of distinction between combatants and civilians – as well as between military objectives and civilian objects – is underscored in Article 48 of AP/I, entitled ‘[b]asic rule’: