Editor's Note: This post is part of the sixth annual Transatlantic Workshop on International Law and Armed Conflict joint blog series.

Nothing in the law of armed conflict precludes belligerents from conducting military operations in densely populated areas or from contesting the urban environment. This is unlikely to change in the foreseeable future. States will seek to retain the freedom to take offensive action against adversaries operating from built-up areas and to defend their own urban centres against invaders. The fate of civilians caught up in urban combat will therefore depend largely on how belligerents implement the rules governing the conduct of hostilities.

Authorities defending urban areas often find themselves in a better position to protect the civilian population than the attacking party. They may have at their disposal more comprehensive information about the location of civilians. They should have a better understanding of civilian needs and infrastructure vulnerabilities. They are also likely to be better placed to provide humanitarian relief. Of course, these assumptions do not always hold true. A city or town might change hands repeatedly. An invading force will not necessarily gain a better understanding of civilian needs just because the fortunes of war have suddenly cast it into the role of a defender. Nevertheless, certain obligations imposed by the law of armed conflict are of greater relevance to defenders than to attackers. The purpose of this post is to explore whether these obligations are adequate.

Offence or Defense: Does the Law Care?

Even though the law of armed conflict does not systematically distinguish between defenders and attackers, it has always imposed differentiated rights and obligations in certain areas. The Hague Regulations of 1907 offer a prominent example. Pursuant to Article 27, belligerents must take all necessary steps during sieges and bombardments “to spare, as far as possible, buildings dedicated to religion, art, science, or charitable purposes, historic monuments, hospitals, and places where the sick and wounded are collected, provided they are not being used at the time for military purposes.” Under the rules of land warfare applicable at the time, defended localities were open to bombardment in their entirety. There could be little hope, therefore, that an attacking party would spare protected buildings and places unless that party was aware of their exact location within the besieged locality. No doubt for this very reason, Article 27 imposes a duty on the besieged party to indicate the presence of protected buildings and places by marking them with distinctive and visible signs.

During the more recent evolution of the law, the distinction between defenders and attackers has receded into the background, most likely for three reasons. First, there is a risk of conflating the distinction between defending and attacking parties with the distinction between states acting in self-defence and those guilty of aggression under the jus ad bellum. This impression is best avoided, since it could call into question the equal application of the law of armed conflict. Second, while states may be waging offensive or defensive campaigns, this does not mean that all their operations are necessarily offensive or defensive in character. As classic writers already recognized, states may take offensive action even while waging a defensive war (see Bluntschli, Das moderne Völkerrecht der civilisirten Staten, § 521). This simple truth lies at the heart of Article 49 of Additional Protocol I, which defines attacks as “acts of violence against the adversary, whether in offence or in defence.” Third, in response to the emergence of air warfare, the law of targeting has transitioned from a locality-based to a point-based approach, encapsulated in the notion of military objectives in Article 52(2) of Additional Protocol I. As a result, the difference between defended and undefended localities, and between defenders and attackers, has lost most of its significance.

Today, the distinction between defensive and offensive military action remains significant to the extent that certain rules of the law of armed conflict continue to draw such a distinction either expressly or by implication. For example, under Article 56(5) of Additional Protocol I, a belligerent is entitled to erect military installations near works or installations containing dangerous forces for the sole purpose of defending them from attack. Other rules may be particularly relevant to defenders. For instance, Article 14 of the Fourth Geneva Convention stipulates that in time of peace, the High Contracting Parties—or after the outbreak of hostilities, the belligerent parties—may establish hospital and safety zones in their own territory. Given its geographical scope, this provision applies predominantly to states defending their national territory.

Article 58 of Additional Protocol I

Leaving aside Article 27 of the Hague Regulations, a common feature of the rules mentioned so far is that they confer rights or liberties on defenders without, however, imposing obligations. The one rule that bucks this trend is Article 58 of Additional Protocol I, which requires all parties to take certain precautions against the effects of attacks, to the maximum extent feasible. These precautionary duties bind all belligerents, but they are of particular relevance to defenders, due to the circumstances in which those duties arise.

Removal of Civilians and Civilian Objects

Pursuant to Article 58(a), the parties must endeavour to remove the civilian population, individual civilians and civilian objects under their control from the vicinity of military objectives. It is important to underline that a party is not required to evacuate civilians or civilian objects from any built-up area as such, but only to remove them from the vicinity of military objectives.

A defending party may go further and evacuate civilians in accordance with Article 17 of the Fourth Geneva Convention—a point reinforced by the reference to Article 49 of the Convention made in Article 58(a)—but it is not obliged to do so. Since civilian objects may qualify as military objectives, Article 58(a) requires defenders to constantly re-assess the tactical situation in order to identify known or anticipated military objectives and act accordingly.

What amounts to the “vicinity’”of a military objective should be understood in a light of the purpose of Article 58, which is to protect the civilian population from the effects of war. The appropriate distance between civilians and a military objective therefore lies at a point where the defending party would no longer expect civilians to suffer harm as a result of friendly or hostile fire directed against that particular military objective.

Military Objectives In or Near Densely Populated Areas

Article 58(b) directs the parties to avoid locating military objectives within or near densely populated areas. At the diplomatic conference, several states voiced concerns that this obligation could curtail their right to take the most efficient measures necessary for the defence of their national territory. Since the precautionary duties under Article 58 apply only to the maximum extent feasible, France suggested in the case of densely populated territories such as those of metropolitan France, Article 58(b) “could not really become operative” at all (Official Records of the Diplomatic Conference, Vol 6, 213). Italy declared that “it is clear that a State with a densely populated territory could not allow that provision to hamper the organization of its defence” (ibid, 235). The Republic of Korea expressed its understanding that Article 58(b) imposes no restrictions on military installations on a state’s own territory (ibid, 235), while the Cameroonian delegation took the view that this provision “can in no way restrict the right of a Party to the conflict to organize its national defence in what it considers to be the most adequate manner” (ibid, 239).

Contrary to the statement by the Republic of Korea, nothing in the language of Article 58(b) precludes it from applying to a defending party within its own national territory. Also, contrary to what Cameroon suggested, Article 58(b) does in fact restrict the right of a contracting party to organise its territorial defence in any way it sees fit. However, as France emphasized, the obligation extends only to what is feasible—which is generally understood to demand only measures that are “practicable or practically possible, taking into account all circumstances existing at the relevant time, including those circumstances relevant to the success of military operations” (ibid, 232).

Whereas feasibility considerations often turn on what is practically possible (for instance, regarding target verification), in the present context the overriding concern will be with what is practicable. Parties to the conflict will have to weigh whether they can avoid placing military objectives within or near densely populated areas without compromising the successful defense of the area. This decision has more to do with a judgment as to what is practicable—all things considered—rather than what is practically possible. Factors that should feed into this assessment include the nature of the military objectives involved, the military significance of the populated area, the hostile action expected from an adversary and the extent and nature of the civilian harm that the placement of military objectives would pose, as well as the availability and effect of any mitigating measures.

In circumstances where locating military objectives within or near densely populated areas cannot be avoided, inspiration may be drawn from Article 57(3) of Additional Protocol I. Thus, where a choice is possible in deciding on the location of a military objective within or near densely populated areas while obtaining a similar military advantage, a location should be selected which may be expected to cause the least danger to civilian lives and to civilian objects.

Other Precautionary Measures

Finally, Article 58(c) requires belligerents to take other necessary precautions to protect the civilian population, individual civilians and civilian objects under their control against the dangers resulting from military operations. This obligation is very broad in scope, in so far as it requires whatever action is necessary to protect civilians and civilian objects from the manifold dangers that result from military operations, subject to the overriding principle of feasibility. Although the rules of the law of armed conflict do not necessarily exhaust the range of measures that belligerents may be required to undertake in this context, they nevertheless serve as a convenient reminder of the steps they ought to consider taking. These include: the establishment of hospital and safety zones, the evacuation of protected persons, seeking free passage of all consignments of medical and hospital stores, measures relating to child welfare, facilitating family news and reunification, the protection of medical units, civil defence activities, and soliciting and conducting relief actions.

Should Rules be More Differentiated?Few rules of the law of armed conflict address the position of defenders in express terms and even fewer impose specific obligations upon them. But this should not be seen as a gap in the law. The distinction between defenders and attackers does not sit well with the general tenor of the law of armed conflict. In fact, many of its rules, such as the duty to take precautions under Article 57 of Additional Protocol I, are context-dependent and thus perfectly capable of imposing differentiated demands on defenders and attackers in line with their specific circumstances. Although not directly addressed to defenders, Article 58 of Additional Protocol I complements these general rules in the context of urban warfare by imposing an obligation on the parties to take precautionary measures to protect civilians and civilian objects under their control, as well as to avoid locating military objectives within or near densely populated areas.

The precautionary duties imposed by Article 58 are broad. Essentially, they demand whatever action is necessary to protect civilians and civilian objects against the dangers arising from military operations. Given their comprehensive scope, efforts to increase the level of protection they offer are best directed at improving their implementation. Currently, violations of Article 58 do not attract individual criminal liability. Professor Eric Talbot Jensen has suggested that criminalizing breaches of Article 58 could go a long way to persuade belligerents to take their obligations more seriously (see Jensen, Precautions against the Effects of Attacks in Urban Areas). This would certainly be a step in the right direction, but it first requires agreement on what concrete measures Article 58 demands, together with the political will to criminalise their non-implementation. It has also been suggested that technological developments might assist with the better identification and location of civilians in urban warfare. This may well be the case, but persuading belligerents that Article 58 requires them to seek and apply such technological solutions would seem to be a necessary first step.

With this in mind, in the immediate future, the best hope for strengthening the regime of precautionary duties in the context of urban warfare lies in developing a consensus as to exactly what obligations Article 58 imposes. This calls for two lines of effort: a better understanding of the range of precautionary measures that belligerents are expected to adopt, and guidance on how they should apply the feasibility standard to reconcile the competing humanitarian and military considerations that arise.

This blog post was written in the author’s personal capacity.