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Max Planck Encyclopedia of Public International Law [MPEPIL]

Asymmetric Warfare

Wolff Heintschel von Heinegg

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2023. All Rights Reserved.date: 03 February 2023

Subject(s):
Combatants — Responsibility of non-state actors — Armed conflict — Belligerence — Geneva Conventions 1949 — Military objectives — Protected persons and property — Occupation — Weapons — Armed attack — Armed forces — Reprisals

Published under the auspices of the Max Planck Institute for Comparative Public Law and International Law under the direction of Professor Anne Peters (2021–) and Professor Rüdiger Wolfrum (2004–2020). 

A.  Concept

Asymmetries in warfare include asymmetry of power, means, methods, organization, values, and time (Pfanner 151). Asymmetry can be participatory, technological, normative, doctrinal, or moral (Schmitt 16). In that sense, wars have always been characterized by at least one form of asymmetry. For instance, any armed conflict involving the United States will by definition be asymmetric because of the technological superiority of the United States armed forces. The same holds true for any armed conflict involving non-State actors—be they partisans, resistance fighters, rebels, insurgents, or terrorists. Moreover, a belligerent may employ methods, strategies, or tactics not envisaged and aiming at the enemy’s vulnerabilities. This is not a novel phenomenon but an intrinsic characteristic of any war (see von Clausewitz Book 3 Chapters 9 and 10).

It therefore seems that the term ‘asymmetric warfare’—by no means a legal term of art—is nothing but a description of a fact of life. In this context, it is, however, important to remember that warfare, especially in Western societies, is perceived as armed hostilities predominantly under State control and between combatants in which civilians and civilian objects are largely spared from violence and destruction (Civilian Population in Armed Conflict). From the outset of its development in the middle of the 19th century the modern law of armed conflict, or international humanitarian law (Humanitarian Law, International), has been based on that approach. To a certain extent the law of armed conflict recognizes, or implicitly accepts, the different forms of asymmetry. Still, its underlying concept is that of symmetric warfare insofar as the use of force is limited to lawful targets (Military Objectives) and that the parties to the conflict will abide by its rules, and be it only because they expect their opponent to act accordingly (Reciprocity). The development of the law of armed conflict has resulted in abolishing the prevalence of military necessity over considerations of humanity (Kriegsräson geht vor Kriegsmanier; Humanity, Principle of) by establishing an operable balance between the two, without making warfare impossible (Dinstein [2016] 8–12).

This approach has been, still is, and will be, challenged by the conduct of hostilities in contemporary armed conflicts that are characterized by an increasingly structured and systematic deviation from the law governing the conduct of hostilities. There is a growing ‘tendency for the violence to spread and permeate all domains of social life. This is because in asymmetrical warfare the weaker side uses the community as a cover and a logistical base to conduct attacks against a superior military apparatus’ (Münkler 20). In asymmetric warfare

the weaker party, recognizing the military superiority of its opponent, will avoid open confrontation that is bound to lead to the annihilation of its troops and to defeat. Instead it will tend to compensate for its inadequate arsenal by employing unconventional means and methods and prolonging the conflict through an undercover war of attrition against its well equipped enemy (Pfanner 153).

As a consequence, there is always a considerable danger that the law of armed conflict will be neglected by all parties to the conflict because its effectiveness and efficiency is, to a certain extent, dependent upon reciprocity or, as formulated by Hersch Lauterpacht: ‘it is impossible to visualize the conduct of hostilities in which one side would be bound by rules of warfare without benefiting from them and the other side would benefit from rules of warfare without being bound by them’ (at 212).

In sum, the term asymmetric warfare may be understood to apply to armed hostilities in which one actor/party endeavours to compensate its military, economic, or other deficiencies by resorting to the use of methods or means of warfare that is not in accordance with the law of armed conflict, or with other rules of public international law. It is important to stress that the motives or strategic goals of asymmetric warfare, while important to understand, are irrelevant from a legal point of view.

B.  Law of Armed Conflict

Many of the atrocities committed during World War II were justified as legitimate responses to the conduct of asymmetric warfare by the respective opponent (Reprisals). For example, partisan attacks lead to the killing of hostages and other innocent civilians or to the wanton destruction of villages in territory occupied or under the control of the German Wehrmacht (see Trial of German Major War Criminals [Judgment] 229 et seq; Collective Punishment; Occupation, Belligerent). The law of armed conflict has been progressively developed in order to eliminate such conduct in future armed conflicts. On the other hand, the law of armed conflict has almost never been modified with a view to compensate technological dissimilarities between the parties to the conflict. For example, the United Kingdom continuously endeavoured to outlaw submarines as means of naval warfare because they posed a considerable threat to its superior surface forces (Submarine Warfare). Those efforts were in vain. Since the law of armed conflict accepts technological asymmetries they do not justify a modification of the law.

Hence, the law of armed conflict accepts asymmetries in warfare, be they technological or doctrinal, and it reacts to such asymmetries only if there is a necessity of preserving minimum standards of humanity or of ‘alleviating as much as possible the calamities of war’ (see Declaration Renouncing the Use in Time of War of Explosive Projectiles under 400 Grammes Weight). Moreover, the law of international armed conflict aims at maintaining the public character of warfare by indirectly reserving the right to harm the enemy to a limited group of actors (Belligerency).

1.  Equal Application of the Law of Armed Conflict

The law of armed conflict applies to every situation amounting to an armed conflict (Armed Conflict, International; Armed Conflict, Non-International), irrespective of the political or strategic goals pursued and irrespective of the legality of the resort to armed force by either of the belligerents. Therefore, in principle, moral or normative asymmetries are irrelevant although they may have a considerable political and strategic impact.

In its preamble, the Geneva Conventions Additional Protocol I (1977) (‘Additional Protocol I’) provides that

the provisions of the Geneva Conventions of 12 August 1949 and of this Protocol must be fully applied in all circumstances to all persons who are protected by those instruments, without any adverse distinction based on the nature or origin of the armed conflict or on the causes espoused by or attributed to the Parties to the conflict.

The principle of equal application of the law of armed conflict is customary in character and, as far as international armed conflicts are concerned, not limited to the rules and principles serving a genuinely humanitarian purpose. This means that the alleged aggressor, as well as the alleged victim of aggression, are equally bound by the law of armed conflict. It also means that they are entitled to make full use of that law by employing the entire spectrum of methods and means of warfare not prohibited under that law (Warfare, Methods and Means). This may, in theory, be different if there has been an authoritative decision by the UN Security Council identifying one party to the conflict as having resorted to an illegal use of force under the United Nations Charter (Peace, Breach of; Use of Force, Prohibition of; United Nations, Security Council). However, if there has been no such determination the right of belligerents to choose methods and means of warfare is not limited by the ius ad bellum. It is only limited by the ius in bello (Art. 22 Regulations concerning the Laws and Customs of War on Land annexed to the 1907 Hague Convention IV respecting the Laws and Customs of War on Land [‘Hague Regulations’] and Art. 35 (1) Additional Protocol I). This also holds true for a resort to armed force authorized or mandated by the UN Security Council. As emphasized in the 1999 UN Secretary-General’s Bulletin, the ‘fundamental principles and rules of international humanitarian law … are applicable to United Nations forces when in situations of armed conflict they are actively engaged therein as combatants, to the extent and for the duration of their engagement’ (UN Secretary-General’s Bulletin of 6 August 1999 on Observance by United Nations Forces of International Humanitarian Law Section 1.1) (United Nations, Secretary-General).

Moreover, the causes for a resort to armed conflict have no impact on the scope of applicability of the law of armed conflict. There have been allegations that military operations aiming at the protection of human rights are governed by stricter legal limitations than ‘regular’ armed conflicts (Thürer 11). State practice, eg in the context of the Kosovo Campaign, provides no sufficient evidence that such allegations have a basis in the existing law.

10  Other normative asymmetries may have an impact on the law of armed conflict. Such normative asymmetries occur if the parties to an international armed conflict are not bound by the same treaties. As in general international law, treaties of the law of armed conflict only apply to States Parties unless a State not party to a given treaty expressly accepts and applies it (see, eg, Art. 6 1907 Hague Convention IV; Art. 96 (2) Additional Protocol I). Such declaration absent, the hostilities will only be governed by customary international (humanitarian) law (Customary International Law). However, treaties do not become inapplicable if members of an alliance (Alliances) or of a combined military operation are not bound by the same treaties. The ensuing problems for inter-operability are often solved by a ‘matrix’ solution. This means that the force commander will entrust those units with a given task whose States are not bound by certain treaty restrictions. The legality of such conduct has been recognized by Art. 21 (3) Convention on Cluster Munitions which provides:

Notwithstanding the provisions of Article 1 of this Convention and in accordance with international law, States Parties, their military personnel or nationals, may engage in military cooperation and operations with States not party to this Convention that might engage in activities prohibited to a State Party.

Finally, States may differ on the interpretation of a treaty they are equally bound by, or of a rule of customary international humanitarian law. Again, the problem of inter-operability is very often solved by either national caveats or by other procedural safeguards like the ‘matrix’ solution.

2.  Actors

11  It is one of the characteristics of asymmetric warfare that the ‘dividing line between combatants and civilians … is consciously blurred and at times erased’ (Pfanner 153). This inevitably results in attacks against the civilian population and individual civilians or even in conduct amounting to—prohibited—perfidy. Such conduct is far from new. The existing law of armed conflict is based on the experience of past armed conflicts and it has, in principle, preserved the general distinction between protected civilians on the one hand and persons who, either as combatants or as members of organized armed groups or as civilians, take a direct part in hostilities on the other hand (see also Civilian Participation in Armed Conflict; Protected Persons.)

(a)  International Armed Conflict

12  Art. 43 (2) Additional Protocol I provides: ‘Members of the armed forces of a Party to a conflict (other than medical personnel and chaplains …) are combatants, that is to say, they have the right to participate directly in hostilities’. This provision may not be misunderstood as being constitutive for the right of taking belligerent measures. Rather, it emphasizes the special legal status combatants enjoy under the law of international armed conflict. As a consequence, combatants may not be prosecuted and punished for their conduct (unless it amounts to a war crime [War Crimes]) and they are entitled to prisoner of war status when captured by the enemy (Prisoners of War). This presupposes that they have distinguished themselves properly, by a fixed distinctive sign or a uniform, and carried their arms openly.

13  Under the law of international armed conflict, there is no prohibition of making use of persons other than members of the regular armed forces. However, such persons only enjoy combatant immunity and prisoner of war status if they are members of militias or volunteer corps forming part of the regular armed forces or if they are members of other militias or voluntary corps, including organized resistance movements, that belong to a party to the conflict and that fulfil the conditions laid down in Art. 4 (A) (2) Geneva Convention relative to the Treatment of Prisoners of War (‘Geneva Convention III’; Geneva Conventions I–IV [1949]). These provisions are a consequence of the experience of World War II. However, in view of the strict conditions prisoner of war status and combatant immunity continue to be limited to a rather small group of actors in international armed conflicts.

14  Art. 44 (3) Additional Protocol I is also to be considered an adaptation of the law of armed conflict to the changed realities of war (Sandoz paras 1697 et seq). While Art. 44 (3) Additional Protocol I does not reflect customary international law, it needs to be stressed that the scope of applicability of this provision is limited to situations dealt with in Art. 1 (4) Additional Protocol I (‘internationalized’ armed conflicts; Ipsen 89 et seq). Still, it extends a certain degree of protection to members of organized armed groups (Guerrilla Forces) who deliberately decide to disregard the minimum requirements set out in this provision (Oeter 59–61).

15  It follows from the foregoing that persons directly participating in the hostilities who neither qualify as combatants nor as members of any of the other privileged groups do not enjoy combatant immunity or, when captured by the enemy, prisoner of war status. As far as civilians are concerned, this has been expressly recognized by Art. 51 (3) Additional Protocol I: ‘Civilians shall enjoy the protection afforded by this Section, unless and for such time as they take a direct part in hostilities’. The exact meaning and scope of the concept of direct participation in hostilities is far from settled (Melzer [2009] 41–68). The same holds true with regard to the legal status of a civilian directly participating in hostilities. Some continue to consider them as civilians protected under the Geneva Convention relative to the Protection of Civilian Persons in Time of War (‘Geneva Convention IV’) who may, however, be attacked (for such time they are directly participating in hostilities) and punished for their conduct (Melzer [2009] 65–85). Others consider them ‘unlawful combatants’ who are not protected by either Geneva Convention IV or Geneva Convention III (Dinstein [2007] 149; see Combatants, Unlawful).

16  Accordingly, the law of international armed conflict provides a rather elaborated set of rules responding to participatory asymmetry and offering an operable solution to most of the problems encountered in recent international armed conflicts. While there is no prohibition of entrusting non-combatants with the commitment of acts harmful to the enemy, persons not enjoying combatant immunity but directly participating in hostilities must be aware that they enjoy no protection under the law of armed conflict beyond the minimum standards laid down in Art. 75 Additional Protocol I and in common Art. 3 Geneva Conventions I–IV. Hence, members of organized armed groups that do not belong to a party to the conflict but who directly participate in the armed hostilities do not pose an insurmountable problem. Either they are to be considered civilians directly taking part in the hostilities who, for the duration of their direct participation, are liable to attack and who may be prosecuted after capture, or the organized armed group they belong to is a party to a non-international armed conflict that exists side by side with the international armed conflict. Then, the members of such a group, at least if and as long as they perform a ‘continuous combat function’ within the organized armed group (Melzer [2009] 16 and 33–36), are legitimate targets who neither enjoy combatant immunity nor prisoner of war status after capture.

(b)  Non-International Armed Conflict

17  Non-international armed conflicts are asymmetric by nature, especially if regular armed forces are engaged in hostilities against organized armed groups. Since, however, the concept of ‘combatant’ does not apply to non-international armed conflicts the applicable law is not built on the legal status of the actors. It is important to note in this context that the very existence of a non-international armed conflict presupposes that there exists at least one organized armed group engaging in armed hostilities against the government or against another organized armed group. Hence, members of an organized armed group do not qualify as civilians. This is widely accepted. However, there is one unresolved issue relating to those members of an organized armed group who do not perform a continuous combat function. While some prefer to consider them civilians (Melzer [2009] 20–40) others are unwilling to differentiate according to an individual’s function within the group (Dinstein [2007] 149). The least common denominator is that members of an organized armed group performing a continuous combat function in a non-international armed conflict do not enjoy general protection but are liable to attack. Of course, the State party to a non-international armed conflict is not prevented from prosecuting them after capture under its domestic criminal law.

18  In non-international armed conflict civilians enjoy general protection. However, they may lose that protection if they deliberately decide to take a direct part in the hostilities. Accordingly, Art. 13 (3) Geneva Conventions Additional Protocol II (1977) provides: ‘Civilians shall enjoy the protection afforded by this part, unless and for such time as they take a direct part in hostilities’. This is declaratory for customary international law (Henckaerts and Doswald-Beck [ed] Rule 6).

3.  Principle of Distinction, Proportionality, Precautions in Attack

(a)  Principle of Distinction

19  Asymmetric actors in armed conflict either deliberately disregard the principle of distinction or they endeavour to incite their opponent to act in violation of that ‘intransgressible’ (Legality of the Threat or Use of Nuclear Weapons [Advisory Opinion] para. 79) principle of the law of armed conflict (see also Indiscriminate Attack).

20  The principle has two implications. On the one hand, it obliges combatants and members of organized armed groups to distinguish themselves from the civilian population. On the other hand, it obliges the parties to the conflict at all times to distinguish between the civilian population and combatants, including members of organized armed groups, and between civilian objects and military objectives, Art. 48 Additional Protocol I.

21  The law of armed conflict provides a rather clear response to any form of asymmetric warfare that aims at blurring the principle of distinction—be it by way of disguising as civilians, be it by abusing civilian objects for military purposes, be it by direct attacks against the civilian population or individual civilians. In this context it may be recalled that a civilian object becomes a lawful target if, by its use, location, or purpose, it makes an effective contribution to the enemy’s military action and if its destruction or neutralization offers a definite military advantage. Still, the problems in practice subsist. If it is not feasible to identify enemy combatants or members of enemy organized armed groups because they appear to be civilians, a decision not to attack may result either in suicide or, even worse, in—prohibited—direct attacks against the civilian population. Of course, combatants who do not distinguish themselves properly when engaged in hostilities do not enjoy combatant immunity or prisoner of war status when captured (Geiß 764). While they may be prosecuted for their conduct this is by many operators considered an insufficient response to their practical problems.

(b)  Proportionality

22  As already seen in the context of ‘human shields’, the law of armed conflict does not prohibit attacks against lawful targets that result in the incidental loss of civilian life, injury to civilians, or damage to civilian objects (Human Shields). Such ‘collateral damage’ is in violation of the law of armed conflict only if it is excessive (in contrast to ‘extensive’) in relation to the concrete and direct military advantage anticipated, Art. 51 (5) (b) Additional Protocol I. In view of that prohibition and in view of the media’s attention to any civilian losses in armed conflict, an asymmetric actor will either seek to prompt the opponent to cause excessive collateral damage or to make the public believe that an attack has been disproportionate. Especially systematic violations of the principle of distinction entail the considerable risk that the opponent applies different standards for the assessment of proportionality. ‘If such tactics are systematically employed for a strategic purpose, the enemy may feel a compelling and overriding necessity to attack irrespective of the anticipated civilian casualties and damage’ (Geiß 766).

23  Still, the prohibition of excessive collateral damage is clear. Considerations of military necessity do, of course, play an important part, especially with regard to the determination of the anticipated military advantage. However, military necessity as such does not justify a deviation from well-established humanitarian standards of the law of armed conflict (Rogers 4).

(c)  Precautions

24  Asymmetric actors will in many cases deliberately act contrary to their obligation to take feasible precautions in attack, especially by abusing civilians or civilian objects as shields or by transferring military objectives into densely populated areas. Despite the obvious illegality of such conduct the opponent will be prevented from attack if the attack is to be expected to result in excessive collateral damage. Here the law of armed conflict itself introduces an element of asymmetry by privileging illegal conduct.

25  Another problem exists with regard to the obligation of the attacker to do everything feasible to limit attacks to lawful targets and to avoid, and in any event to minimize, excessive collateral damage, Art. 57 (2) Additional Protocol I. ‘Feasible precautions’ have been defined as ‘those precautions which are practicable or practically possible taking into account all circumstances ruling at the time, including humanitarian and military considerations’, Art. 3 (4) original Protocol II on Prohibitions or Restrictions on the Use of Mines, Booby-Traps and Other Devices (adopted together with the Convention on Prohibitions or Restrictions on the Use of Certain Conventional Weapons which may be Deemed to be Excessively Injurious or to have Indiscriminate Effects [‘CCW Convention’]) and Art. 3 (10) amended Protocol II. It would go too far to conclude that parties to a conflict disposing of advanced weapons systems are under an absolute obligation to only make use of sophisticated and highly discriminating weapons. The fact that such weaponry is available does not necessarily mean that less sophisticated weapons may not be employed any longer. Sophisticated and advanced weapons are considerably expensive and they may, therefore, be reserved for attacks on more important targets. It may not be left out of consideration, however, that

advanced militaries are held to a higher standard—as a matter of law—because more precautions are feasible. As the gap between ‘haves’ and ‘have-nots’ widens in 21st century warfare, this normative relativism will grow. In a sense, we are witnessing the birth of a capabilities-based IHL regime (Schmitt 42).

The consequence is that the standard of feasibility, to a certain extent, privileges the weaker or technologically less developed side of an armed conflict and thus adds another form of normative asymmetry in armed conflict.

4.  Methods and Means of Warfare

(a)  Means of Warfare

26  The law of armed conflict and arms control law (both increasingly merging to a single regime) provide a well-established set of rules that either prohibit the use of certain weapons or that restrict their use in certain circumstances. In asymmetric warfare the weaker party may be inclined to disregard such prohibitions or restrictions and to justify a deviation with the superiority of the respective opponent (Geiß 758). Moreover, as pointed out by the International Committee of the Red Cross (ICRC), ‘it is evident that if one Party, in violation of definite rules, employs weapons or other methods of warfare which give it an immediate, great military advantage, the adversary may, in its own defence, be induced to retort at once with similar measures’ (Reaffirmation and Development of the Laws and Customs Applicable in Armed Conflicts 83). In other words, the misuse of weapons will, as a rule, invite belligerent reprisals. However, such justifications have no basis in the existing law. The fact that a party to an armed conflict is confronted with a superior enemy does not justify the use of means of warfare whose use is prohibited under the law of—international or non-international—armed conflict. Therefore, the threat of imminent defeat is no sufficient ground for resorting to the use of prohibited means of warfare.

27  Unfortunately, the International Court of Justice (ICJ), in its Legality of the Threat or Use of Nuclear Weapons (Advisory Opinion), has ruled that the use of nuclear weapons ‘would generally be contrary to the rules of international law applicable in armed conflict, and in particular the principles and rules of humanitarian law’, unless the ‘very survival of a State would be at stake’ (at 266; Nuclear Weapons Advisory Opinions). It is obvious that this ruling may be abused for justifying a violation of the rules and principles of the law of armed conflict. It needs to be emphasized, however, that the ICJ’s finding has no basis in the law of armed conflict. If at all, the survival argument may be of relevance for the ius ad bellum.

(b)  Methods of Warfare

28  The asymmetric character of an armed conflict does not justify the use of methods of warfare prohibited under the law of armed conflict. Therefore, starvation of civilians as a method of warfare, or to order that there shall be no survivors, is prohibited under all circumstances (Arts 40 and 54 (1) Additional Protocol I, Art. 23 (d) Hague Regulations; Henckaerts and Doswald-Beck [eds] Rules 46 and 53).

29  One feature of asymmetric warfare are suicide bombings, another is the use of ‘human shields’. With regard to the former it is important to note that the law of armed conflict does not prohibit suicide attacks unless they are conducted by resort to perfidy (Schmitt 32). This is different with regard to the use of ‘human shields’. Art. 51 (7) Additional Protocol I, that reflects customary international law, prohibits the use of the ‘presence or movements of the civilian population or individual civilians … to render certain points or areas immune from military operations, in particular in attempts to shield military objectives from attacks or to shield, favour or impede military operations’ (see also Art. 28 Geneva Convention IV). The law of armed conflict provides a possible—though not undisputed—solution for coping with the issue of ‘human shields’ by distinguishing between voluntary and involuntary human shields. Civilians, whatever their motives, voluntarily serving as human shields may be considered as taking a direct part in hostilities who, for the duration of such participation, lose their protected status under the law of armed conflict. Accordingly, voluntary human shields are targetable and they are not included in the estimation of incidental injury when assessing proportionality (Dinstein [2016] 183). Against allegations to the contrary, involuntary human shields maintain their status as civilians (Schmitt 27). Accordingly, attacks against a shielded military objective will be prohibited if the incidental losses among the involuntary human shields are excessive in relation to the concrete and direct military advantage anticipated (Art. 51 (5) (b) Additional Protocol I). However,

the appraisal whether civilian casualties are expected to be ‘excessive’ in relation to the anticipated military advantage must make allowances for the fact that, by dint of the presence (albeit involuntary) of civilians at the site of the military objective, the number of civilian casualties can be foreseen to be higher than usual (Dinstein [2016] 185).

30  Sometimes, especially if they do not act overtly, the distinction between involuntary and voluntary human shields will not provide an operable solution in practice, because it may be impossible to determine whether a person has deliberately and freely decided to serve as a human shield. Moreover, the law of armed conflict may not prohibit a proportionate attack against a shielded lawful target but it will prove a most difficult task to defend the death of a considerable number of civilians politically. In asymmetric warfare the weaker party often consciously and systematically turns to the practice of using human shields in order to exploit the political and moral dilemma the attacker will find himself in. The law may offer a solution. However, that will, in most cases, not assist in overcoming the said dilemmas.

31  Finally, some States respond to asymmetric threats by resorting to targeted killings of individuals suspected of being involved in unlawful attacks against government forces, civilians, or civilian objects (Targeted Killing). It must be borne in mind that under the law of armed conflict there is no general prohibition of targeted killings. If the respective individual qualifies a lawful military target, especially as a member of an organized armed group (performing a continuous combat function) or a civilian directly participating in hostilities, he or she may be attacked. While some authors maintain that there is an obligation to rather capture than kill the individual if that proves to be a feasible alternative (for an in-depth analysis see Melzer [2008] 394–419), this position does not reflect the law of armed conflict as it currently stands.

5.  Need for Reform of the Law of Armed Conflict?

32  Some doubts have been expressed whether asymmetric warfare ‘could still be grasped by and measured against the concept of military necessity, for the complexities and intangibility of such scenarios escape its traditionally narrow delimitations’ (Geiß 770). Especially non-State actors deliberately and systematically deviate from well-established standards of the law of armed conflict and, thus, induce their opponents to re-emphasize considerations of military necessity that may result in either a more liberal interpretation of the law of armed conflict, or in its irrelevance, because it is considered an unfair obstacle to the success of military operations in armed conflict.

33  Of course, reciprocity is an important factor for the continuing effectiveness of the law of armed conflict. If one party to an armed conflict deliberately and systematically disregards its rules and principles in order to achieve a military or political advantage, the opponent’s readiness to continue to comply with the law may steadily decrease. There are, however, solutions to the problem. On the one hand, the law of armed conflict is flexible enough to respond to an asymmetric actor’s conduct. While it is true that such responses put a heavier burden on the law-abiding party to the conflict, the values underlying the law of armed conflict and the achievements of the past 150 years should not be given up too easily. Moreover, the emergence of international criminal law has added a further and powerful enforcement mechanism for ensuring compliance with the law of armed conflict. On the other hand, it is well perceivable that non-State actors will understand that, despite their inferiority in arms and military technology, they will ultimately profit from compliance with the law of armed conflict unless they deliberately choose to be considered ordinary or war criminals. Nevertheless, there is no doubt that the growing asymmetries in warfare have the potential of shaking the very bases of the law of armed conflict. This, however, does not mean that there is a need for an adaptation of the law to the ‘new realities’ of armed conflict (Schaller 29–31).

C.  Situations not Governed by the Law of Armed Conflict

34  It is true that, at present, the world is witnessing a privatization and demilitarization of war (Münkler 15–21). Moreover, so-called ‘transnational wars’ (ibid 20) often do not fulfil the rather strict criteria for the applicability of the law of armed conflict. Therefore, the law of armed conflict is inapplicable to those situations of asymmetric warfare, eg transnational terrorism and the ‘Global War on Terror’, not amounting to an international or non-international armed conflict. On the other hand, terrorists employ methods and means that have so far been reserved to regular armed forces and governments increasingly make use of their armed forces in order to counter the terrorist threat. By policy, not by law, some governments instruct their armed forces to apply the law of armed conflict in counterterrorism operations. This practice by its very nature has not resulted in widening the scope of applicability of the law of armed conflict. Only at first glance does this practice seem to be guided by prudence. Of course, armed forces are trained in the application of the law of armed conflict. Moreover, it is quite convincing to argue that in case of doubt compliance with the law of armed conflict puts the armed forces on the safe side, especially when it comes to the use of methods and means of warfare. However, the law of armed conflict will never be applied in its entirety and considerations of military necessity that may be justified in counterterrorism operations could all too easily have negative repercussions on the law of armed conflict when applied in situations of armed conflict proper. At the same time, most States whose armed forces are engaged in counterterrorism operations reject an application of the law of armed conflict and either rely on the right of self-defence or they additionally accept the application of human rights to such operations. This, however, does not contribute to legal clarity either. The right of self-defence is far too vague than to provide operable solutions to the problem of the legality of the use of force (eg targeted killings, see Melzer [2008] 222–39) or of other measures taken against terrorists. Human rights, of course, limit the exercise of jurisdiction vis-à-vis individuals. However, their unmodified application to counterterrorism operations rather than providing the necessary answers privileges the terrorists who are not deterred by the threat of criminal prosecution. It is, therefore, necessary for States to agree on international standards and criteria that specifically apply to counterterrorism operations. Such standards and criteria absent the armed forces entrusted with countering the terrorist threat will in most cases operate in a legal vacuum, at least in an intolerable legal grey area.

D.  Concluding Remarks

35  Asymmetric warfare clearly constitutes a challenge to the international legal order and to its underlying values. While it does not justify a deviation from well-established rules and principles of the law of armed conflict it is necessary to strengthen that law by offering incentives, especially to non-State actors, to comply with that law if it is applicable ratione materiae. This finding does not relieve States from their obligation vis-à-vis their armed forces to clarify the applicable law for situations not amounting to an international or non-international armed conflict. Moreover, governments ought to scrupulously scrutinize and evaluate the challenges posed by asymmetric warfare, take the necessary measures, and reduce their vulnerabilities. Vulnerabilities—whatever their nature—will always be an interesting target for asymmetric actors, be they weaker enemies, or be they terrorists.

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