The Use of Force Against Non-State Actors Under International Law: An Analysis of the U.S. Predator Strike in Yemen

By Norman G. Printer, Jr. FNa1

Contents

Page

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

II. Background on the Strike in Yemen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

III. The Jus Ad Bellum and the Strike in Yemen . . . . . . . . . . . . . . . . . . . . . . . . . 8

A. The Use of Force Paradigm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1. U.N. Charter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2. Customary International Law . . . . . . . . . . . . . . . . . . . . . . . . . . 12

B. The Use of Force Paradigm and Terrorist Organizations . . . . . . . . . 17

1. U.N. Charter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2. Customary International Law . . . . . . . . . . . . . . . . . . . . . . . . . 27

C. Applying the Jus Ad Bellum to the Strike in Yemen . . . . . . . . . . . . . 28

IV. The Jus In Bello and the Strike in Yemen . . . . . . . . . . . . . . . . . . . . . . . . . . 36

A. The Law of Armed Conflict . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

1. General Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

2. Conventional Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

(a) The Hague Conventions and the Definition of Combatants . 41

(b) The Geneva Conventions and Protected Persons . . . . . . . . 44

3. The Significance of Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

B. Applying the Jus In Bello to the Strike in Yemen . . . . . . . . . . . . . . . . . . 50

1. Status of al-Qaeda Members under LOAC . . . . . . . . . . . . . . . . . . . 52

2. Significance of Status as Unlawful Combatants . . . . . . . . . . . . . . . . 59

3. Considerations of Military Necessity, Discrimination,

and Proportionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

V. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

I. Introduction

Last November, a Predator unmanned aerial vehicle operated by American forces fired a Hellfire missile at a car in Yemen, killing six suspected members of the al-Qaeda terrorist organization.[1] Sources both domestically and abroad criticized the strike, aimed at one of Osama bin Laden’s top lieutenants, as an extrajudicial killing or assassination in violation of international law.[2] This paper will examine whether the attack was contrary to international law and will describe principles of legal analysis likely to be most relevant in future armed conflict between states and non-state actors in the global “War on Terror.”[3]

A legitimate use of transnational military force must comply with two general requirements, the jus ad bellum and the jus in bello.[4] The jus ad bellum are the rules by which a state may lawfully resort to the use of armed force in the international arena.[5] The jus in bello establishes the modalities of conflict once hostilities have been initiated.[6] Only after examining these two separate and distinct concepts can one ascertain whether the U.S. strike in Yemen comported with international law.[7]

The next section, Section II, consists of a brief factual primer on the attack in Yemen. Section III discerns the jus ad bellum in light of the use of force paradigm established by the U.N. Charter[8] and extant customary law, and specifically whether the U.S. military response against al-Qaeda following the terrorist attacks of September 11, 2001 is justified as a proper invocation of the right to self-defense. An analysis of these issues concludes that the use of force paradigm as established by the U.N. Charter and extant customary law, applies to military conflicts between state and non-state actors. In particular, the Charter’s use of force provisions should apply to terrorist groups as a matter of customary law because groups that can carry out armed attacks that threaten global peace and security should be bound by the very provisions that seek to constrain such behavior. Although non-state actors are not traditionally subject to provisos involving the interstate use of force, the current legal construct must evolve such that the application of the use of force paradigm depends upon the nature of the armed coercion and not on the legal status of the organization using force. These considerations dictate that the jus ad bellum applies to the on-going conflict between the U.S. and al-Qaeda. Section III concludes that the attack in Yemen was consistent with the jus ad bellum, since September 11 served as a reasonable justification for the U.S.’s choice to resort to self-help, and the self-help attack comported with the customary international law concepts of military necessity and proportionality.

Section IV outlines the jus in bello as found in the Hague and Geneva Conventions, in addition to the relevant customary principles of the laws of armed conflict, and examines the particulars of the strike in Yemen in light of the jus in bello. The law of armed conflict seeks to limit the horrors of war by limiting the modalities of the use of force between belligerents, pursuant to the concepts of necessity, discrimination, and proportionality. The Hague and Geneva Conventions, which afford certain protections to persons who observe the laws and customs of war, have further refined these principles. By definition, terrorists who engage in the interstate use of force do not observe the laws of war. Therefore, they are not entitled to an elevated status that would grant them protections under the jus in bello. As such, members of terror groups are entitled to fewer rights than protected persons and lawful combatants. Therefore, they may lawfully be targeted in instances of self-defense, provided that the other provisions of the jus in bello are also satisfied. Members of al-Qaeda who actively support and engage in terrorist activities, such as the six men traveling in Yemen, are rightfully considered unlawful combatants. As unlawful combatants, these six men were lawfully targeted by the Predator drone operated by U.S. forces. Moreover, the strike in Yemen was consistent with the customary international law concepts of necessity, proportionality, and discrimination. Section IV then analyzes whether the attack was an assassination or extrajudicial killing in contravention of international law and finds that because attack was carried out in the larger scheme of self-defense, the jus in bello was not violated.

The last section of this article, Section V, examines the jus ad bellum and the jus in bello in the larger context of transnational conflicts between state and non-state actors, before summarizing the international law underpinnings of the strike in Yemen.

II. Background on the Strike in Yemen

The strike in Yemen was aimed at Ali Qaed Salim Sinan al-Harethi, the leader of the al-Qaeda organization in Yemen,[9] considered one of the top twelve al-Qaeda figures in the world.[10] Al-Harethi, a former bodyguard to Osama bin Laden, had associated with the top al-Qaeda leader for over twenty years.[11] It is believed that he acted as the "communications coordinator" for the September 11 attacks against the U.S.,[12] and that he played a key role in the October 2000 bombing of the USS Cole that killed 17 sailors and nearly sank the American destroyer,[13] in addition to committing other terrorist acts.[14] Yemen, the ancestral home of Osama bin Laden,[15] is assisting the U.S. in the war on terror but continues to be a haven for al-Qaeda.[16] Previous efforts by the Yemeni government to detain al-Harethi and other suspected terrorists had been unsuccessful[17] and often led to bloody firefights that resulted in the deaths of several police officers and soldiers.[18]

On November 3, 2002, a joint American and Yemeni intelligence team was conduct surveillance on al-Harethi with a Predator unmanned aerial vehicle (UAV).[19] Al-Harethi was traveling in a car with five other suspected al-Qaeda members in northern Yemen.[20] The Predator, which was controlled by CIA operators based at a French military facility in Djibouti,[21] a tiny nation about 160 miles west of Yemen, was operating in Yemeni airspace with the permission of the Yemeni government.[22] Once the car was isolated far from any other traffic, CIA operatives gave the order to fire an air-to-ground Hellfire missile from the Predator at al-Harethi’s car.[23] All six occupants of the car were killed.[24] Al-Harethi’s remains were positively identified.[25] The attack was part of the on-going military conflict between the U.S. and al-Qaeda that began after President Bush declared “war” on terrorism following the events of September 11, 2001.[26] Since the U.S began military operations in Afghanistan on October 7, 2001, over 3,000 suspected terrorists have been captured or killed in action.[27]

III. The Jus Ad Bellum and the Strike in Yemen

Many of those familiar with international law have suggested that there are no rules when dealing with terrorist organizations.[28] This raises the issue of what, if any, norms of international law apply to the military conflict between al-Qaeda and the U.S. To answer this question, the use of force paradigm under the U.N. Charter and extant customary international law[29] will first be examined. Then, provided that some or all of the norms apply, the strike in Yemen will -be analyzed for compliance with the jus ad bellum.

A. The Use of Force Paradigm

1. U.N. Charter: After the scourge of World War II, the international community sought to establish a new normative standard for the use of force between state actors. The result was the U.N. Charter, which unequivocally outlaws the use of aggressive force.[30] The Charter’s mandate under Article 2(4) is clear: “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.”[31] The document, only outlaws the use of aggressive force; it does not outlaw the use of force in its entirety. The Charter recognizes an exception to the general rule by acknowledging the right to self-defense.[32] Specifically, Article 51 provides:

Nothing in the present Charter shall impair the inherent right of individual or collective self-defence [sic] if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence [sic] shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.[33]

The fact that the language states that the right to self-defense is “inherent” suggests that the right, which existed as a matter of customary international law before the Charter was adopted,[34] was incorporated into the Charter[35] and continues to exist independently of the Charter.[36]

Although the Charter provides for the right to self-help, it gives little guidance regarding the modalities of self-defense. The requirement of a condition precedent means that that the right may only be exercised in case of an “armed attack.”[37] However, the Charter does not define what constitutes an “armed attack.”[38] This has left scholars to debate whether the right to use counter force exists only in cases of an armed attack, or whether it may exist in situations other than an armed attack.[39] Regardless, the generally accepted standard is that to constitute an armed attack pursuant to the Charter the aggression must be by armed force and of sufficient magnitude and severity.[40] Admittedly, the determination of whether an aggressive use of force crosses the threshold and triggers the exercise of self-help is a subjective one to be made by the attacked state.[41] Nonetheless, the determination is ultimately subject to legal scrutiny by the international community in conformity with the preceding standard.[42] If an aggressive use of force does not rise to the level of an armed attack, a state may pursue traditional criminal law sanctions, but may not rightfully respond with military action.[43]

Despite the Charter’s recognition of the right of self-defense, the right is not unfettered. The Security Council may intervene by taking “measures,” which would effectively truncate the exercise of self-defense.[44] What constitutes “measures” as contemplated by the Charter is subject to debate, but the language of Article 51 suggests that the Council’s actions must be affirmative acts in furtherance of international peace and security.[45] Indeed, mere words or rhetoric are insufficient to divest a state of the right to self-help.[46] Finally, a state intending to use self-help or engaged in self-help must report its intentions to the Security Council or jeopardize its continued right to use force.[47] Other than the limitations discussed above, the Charter does not delimit the parameters of self-defense.[48]

The use of force regime outlined above is recognized as customary international law, meaning that it is binding upon all states, even those few states that do not belong to the U.N.[49] Although it is still debated whether the Charter intended to codify customary international law as of the Charter’s inception,[50] it is undisputed that all states are bound by the document’s norms. Moreover, nearly all states are members of the U.N.[51] and most of those recognize, if not observe, Articles 2(4) and 51 as the normative standard for the use of force.[52] Furthermore, the Restatement asserts that the Charter norms are generally recognized as jus cogens[53]

2. Customary International Law: Although it is generally accepted that the Charter’s norms have ripened into customary international law, it is less clear whether customary international law has come to reflect the Charter in toto; that is, whether the Charter and customary law have become synonymous.[54] It has been suggested that as of 1945 the U.N. Charter “subsumed” and “supervened” customary rules for the use of force in their entirety.[55] However, any doubt as to the continued viability of customary international law was extinguished by the International Court of Justice in the 1986 case Concerning Military Activities in and against Nicaragua (Nicaragua v. U.S.).[56] In that case, the court considered whether the U.S. properly exercised a right of collective self-defense in aiding Nicaraguan “contras” in response to an alleged armed attack on another state.[57] In reaching a decision, the court stated that rules for the non-use of force “continue to be binding as part of customary international law, despite the operation of provisions of conventional law in which they have been incorporated.” [58] The significance is that when the Charter’s norms do not apply, extant rules of customary international law will govern. Although the court did not fully delineate the customary rules regarding the use of force, it implicitly denied the hegemony of the Charter by recognizing that the Charter and customary norms do not coincide exactly, especially with regard to the right of self-defense.[59] More importantly, the court unambiguously stated that the right of self-defense exists as a matter of customary international law.[60] In short, while scholars continue to debate whether the text of Article 51 is a realistic and workable standard consistent with customary international law,[61] it is plain that the use of force paradigm incorporates conventional and customary law.

Customary international law is all the more important when examining the parameters of self-defense because, as previously recognized, the Charter offers little guidance. Professor L. C. Green summed up the relationship between the two bodies of law on the right of self-defense:

While the Charter restricts the right to resort to measures of a warlike character to those required by self-defense, its provisions only relate to the jus ad bellum. Once a conflict has begun, the limitations of Article 51 become irrelevant. This means there is no obligation upon a party resorting to war in self-defense to limit his activities to those essential to his self-defense. Thus, if an aggressor has invaded his territory and been expelled, it does not mean that the victim of the aggression has to cease his operations once his own territory has been liberated. He may continue to take advantage of the jus in bello, including the principle of proportionality, until he is satisfied that the aggressor is defeated and no longer constitutes a threat.[62]

Without further constraints, the right of self-defense as stated might appear to be relatively open-ended; however, customary law prescribes additional limitations on the resort to self-help. Specifically, “[i]t is a well established rule of customary international law that even when a state is lawfully engaged in the exercise of its inherent right of self-defense, its use of force must be limited to that force necessary to defend against the attack and must be proportionate.”[63] The concept of necessity dictates that military force may be used only when there are no alternative means of redress.[64] That is, if a state perceives that it has no other choice but to use force in self-defense, it may do so, provided that it has exhausted all reasonable peaceful means to resolve the situation[65] and “delay in the use of force would make it impossible to guarantee the defense of the state.”[66] Stated differently, an attacked state may rightfully respond militarily if it reasonably believes that force is the only option available to defeat the enemy and to eliminate or reduce the threat of future attacks.[67] However, in the absence of a continuing threat, the principle of necessity would not justify the use of force. For instance, in the case of a single terrorist attack without the expectation of another attack.[68] Suffice it to say, force may not be used legitimately in reprisal or to simply punish an enemy.[69]

Necessity not only limits the circumstances in which defensive force may be used, but it also acts as a check on the duration in which counter force may be used. By limiting the use of force to circumstances only when necessary, it follows that once military operations have been initiated they must cease when an enemy has been defeated or no longer has the means to fight.[70] In that sense, the concept of necessity effectively imposes a cap on the lawful period of hostilities. For example, a victim state would be required to cease hostilities if the leaders of an opposing force surrendered. Note that the principle of necessity, as a limit on the acceptable duration of hostilities, is outcome determinative—that is, until the enemy is vanquished—and is not temporal in nature. There is no time limit or expiration date that obviates a justified use of counter force.[71] Rather, the test is whether the enemy continues to pose a threat that can only be effectively countered with armed coercion. While the above rule is easy to articulate, its application may be more problematic in that the exact moment when an opposing force poses little to no threat such that necessity no longer justifies military action is arguably more of a policy question than a legal question.[72] Nevertheless, the point is that the concept of necessity regulates the use of defensive force not only as to the initiation of self-help but also as to its continued application.

Another customary international law consideration relevant to the concept of self-defense is the concept of proportionality, which requires that a military response over the course of a conflict is proportionate to the threat posed by the enemy.[73] It is not possible for enemy states to calculate precisely the casualties and damages that they are likely to inflict on each other during the course of a conflict.[74] This “is neither a necessary nor a possible condition.”[75] However, there must be some symmetry between the initial use of unlawful force and the responsive counter force, based upon the gravity of the preliminary attack and the continuing threat posed by the enemy.[76] For instance, a nuclear strike in response to a single terrorist attack in which ten people were killed would be disproportionate.[77] Because it is impossible to know with any degree of certainty at the onset of a conflict what amount of counter force will be required to defeat an aggressor, proportionality is essentially a standard of reasonableness that “must be applied with some degree of flexibility.”[78] Together, the customary international law concepts of necessity and proportionality, in conjunction with the norms established by the Charter, constitute the “use of force paradigm”[79] under international law.

B. The Use of Force Paradigm and Terrorist Organizations

Although the use of force paradigm regulates interstate violence, the question remains whether the paradigm is relevant to conflicts with terrorist organizations, since such groups are non-state actors.[80] If the paradigm is relevant, a secondary issue is whether the paradigm applies to the victimized state, to the terror organization, or to both. The following analysis proffers that conventional and customary use of force provisions should apply to interstate conflicts between state and non-state actors. Specifically, the conflict regime established by U.N. Charter should apply with equal force to non-state actors, such as terrorist organizations, as it does to state actors because to do otherwise would undercut the Charter’s primary purpose, the maintenance of international peace and security. The Charter cannot bind terror groups as a matter of conventional law, in that no such group is a signatory to the Charter. However, the maintenance of global stability dictates that transnational terror networks should be bound by the document’s use of force provisos and other accepted international norms as a matter of customary international law.

1. U.N. Charter: To assess whether the U.N. Charter applies to a conflict with a terrorist organization, on must look to the prohibitive language in Article 2(4), which states that “[a]ll Members shall refrain . . . from the threat or use of force against . . . any state.”[81] Superficially, one could argue that the Charter does not apply to situations involving non-state actors because the language explicitly states that only “members” are bound by its terms, and no non-state actor is a member of the U.N. Moreover, the Charter’s status as a treaty means that, it can only bind states qua states. Therefore, the Charter, is not binding upon non-state actors as a matter of conventional law.[82] To the extent that these points are technically correct, a terrorist organization, as a non-state entity, cannot be bound by the Charter as a matter of conventional law.

The more difficult question is whether the Charter’s norms are controlling as a matter of customary international law in an armed conflict between a state and a terrorist group. As previously discussed, the Charter, as customary law, is binding upon all states, even non-U.N. members.[83] However, the fact that the document’s norms bind all states does not speak to the issue of whether they bind, or should bind, non-state actors. Stated differently, a customary norm that binds all states is not necessarily binding upon a terror group, a non-state entity.

An analysis of the competing arguments suggests that the customary use of force provisions should bind non-state actors. Terrorist organizations that use aggressive force against a state that rises to the level of an armed attack should not escape the very provisos of the Charter that seek to constrain such behavior. There are two interrelated reasons supporting this conclusion. First, an entity that elects to use force on the international plane should be treated as an international actor and should be bound by accepted international norms. This argument is supported by practical considerations.[84] According to Ian Brownlie,

[I]nternational lawyer[s] cannot afford to ignore entities which maintain some sort of existence on the international plane in spite of their anomalous charter. Indeed, the role played by politically active entities such as belligerent communities indicates that, in the sphere of personality, effectiveness is an influential principle.[85]

Second, it would be inconsistent with the purpose of the Charter—the maintenance of international peace and security—to allow terrorist groups that engage in transnational armed conflict against a state to fall outside the Charter.[86] In short, the nature of the terrorist act should dictate whether international norms apply, not the nature of the organization.

The fact that terrorist networks, as private actors, are not generally recognized as subjects of international law should not deter the applicability of the Charter’s norms to such organizations that use transnational force.[87] Ostensibly, the legal issue is the application of public international law to non-state entities that are generally thought of as private actors. Public international law does not typically apply to private entities. However, in the aftermath of World War II, international norms have been able to adapt to unanticipated situations to the point that the line between public and private international law has become increasingly blurred. Matters that were once thought to be issues solely between state actors have devolved to affect private entities and private persons.

At the end of World War II, a state-centered approach to international law that did not recognize the individual as a subject of international law existed. The continuation of this approach would have meant that the Axis leadership would have been largely immune from violations of various international humanitarian norms. However, the post-war jurisprudence evolved such that individuals could be held responsible for violations of international norms, recognizing that individuals were ultimately responsible for the millions of deaths suffered at the hands of the Axis governments.[88] Arguably, if antiquated notions of legal personality had not been revisited at Nuremberg, the International Military Tribunals might not have been constituted and impunity would have prevailed. Fortunately, the legacy of Nuremberg in the twenty-first century is that traditional notions of international legal personality have been severed from sovereignty, so that the state is no longer the sole actor on the international stage.[89]

Just as the jurisprudence at Nuremberg evolved to account for the violation of international norms by previously unrecognized subjects of international law, a similar innovation is warranted to hold terrorist organizations accountable for the unlawful use of force.[90] Admittedly, this might require that terrorist organizations be granted limited international legal personality. While the idea of granting terror groups de jure status does not fit neatly into preconceived notions under the U.N. Charter,[91] it is consistent with the norms that have developed since Nuremberg.[92] To conceptualize the argument that terrorist groups should enjoy some incidents of international legal status, it helps to think of the similarities between terror groups and non-governmental organizations (NGOs). An NGO is an international “organization that is neither affiliated with nor under the direction of a government[,] . . . but rather is composed of private individuals . . . .”[93] Although NGOs do not typically enjoy international legal personality, their status has evolved such that they are increasingly recognized as subjects of international law with some incidents of international legal status.[94] A terrorist network that operates on a global basis, insofar as it is an association of persons with a common purpose not affiliated with a state, arguably has attributes similar to an NGO.[95] It follows that such networks should not be prohibited from possessing some incidents of international legal status, if the consequence is to enhance their accountability under international law. This is not to suggest that a group organized for an illegal purpose, such as a terror organization, should enjoy the same legitimacy as an NGO organized for a legitimate purpose. Instead, error groups should only receive a limited, albeit definite, form of international personality, with a focus on the rights of states and of the international community, to hold such organizations accountable for violations of customary use of force norms.[96]

In addition, if the Charter’s norms were applied to the actions of terror organizations, the purpose of the Charter to maintain international peace and security would be furthered. Conversely, the Charter’s principles would be ill-served if the activities of rogue groups fell outside the document’s norms. A non-state entity that uses deadly force on a global scale can just as easily threaten peace and security just as a state entity can. An armed attack promulgated by a non-state entity is still an armed attack.[97] A state’s national security is no less threatened because the offending organization may not be recognized as a subject of international law.[98]

The whole purpose of permitting a state to use force to defend itself from attack is to prevent massive injury. That injury is no less significant if private rather than public wrongdoers inflict it. In contemporary times, non-state actors are as capable of inflicting widespread injury as many state actors.[99]

Arguably, a terrorist group may pose a greater threat than a state that possesses similar capabilities.[100] Regardless, non-state actors have, as a practical matter, the same potential to wreak havoc with international peace and security as do state actors. Therefore, the Charter’s norms, which seek to limit interstate violence, should apply equally to all transnational acts of armed aggression, regardless of the proponent of the violence.[101] The focus should be on the nature of the violence, not on the legal status of the aggressor. Not operating according to this logic could create a double standard that would require states to follow the Charter’s strictures, while terrorist groups would follow a different set of norms, or perhaps no norms at all. A patchwork of rules would only further muddy the already opaque use of force paradigm, lessening the viability of the Charter and destabilizing the pursuit of international security. However, explicitly incorporating terror networks under the umbrella of the U.N. regime would only fortify the use of force paradigm.

One could contend that holding terror groups accountable to the current conflict regime is unnecessary since the currently existing criminal norms obviate the need to impose the Charter’s standards by serving as a sufficient check on terror.[102] It is true that a member of a terrorist organization can beheld individually accountable through the application of criminal norms, but this argument is not persuasive in that the current use of force regime employs a two-tiered approach to restrain the aggressive use of force by state actors.[103] Specifically, the U.N. Charter and other customary norms impose restraints on the use of force by states qua states.[104] Simultaneously, criminal law norms impose liability on individual state actors, who use force in contravention of international law.[105] For instance, Iraq’s invasion of Kuwait in 1990 violated the U.N. Charter, for which the former state of Iraq could have been held accountable under the theory of state responsibility.[106] Iraq’s deposed leaders could also have been held individually accountable for committing crimes against peace in violation of customary international law.[107] The existence of a multi-tiered system of accountability implicitly rejects a single-tiered approach as insufficient to modify unacceptable forms of behavior vis-à-vis the use of force.

A two-tiered accountability regime should apply to terrorist organizations that commit hostilities on a global scale for the same reason that it applies to state actors at both the individual and governmental level. It is difficult to discern why a two-tiered approach that is deemed necessary to hold state actors accountable is unnecessary to restrain the actions of non-state actors. If anything, a multi-tiered approach is all the more essential to constrain the behavior of terror groups** because such groups have demonstrated that they are less responsible than states when using unlawful force. Moreover, to suggest that criminal norms in and of themselves are sufficient intimates that the jus ad bellum is superfluous--that the U.N. Charter is irrelevant and serves no purpose. This can hardly be the case. If it were, this argument would apply with equal force to hostilities committed by states. That is, if criminal norms were an adequate restraint on terrorists, would they then not also be an adequate restraint on state actors. However, a single-tiered approach to accountability for the use of force has already been rejected implicitly. A more viable explanation would be that while terrorists are subject to individual criminal liability for their actions, there should also be accountability at the organizational level, just as there is for state actors. To do otherwise, would be inconsistent with the current use of force regime.

Finally, it might seem pointless to maintain that an association organized for an unlawful purpose should fall under the auspices of the Charter. However, for the very reason that terrorist groups do not abide by international norms, it behooves the international community to hold such groups accountable to the Charter’s directives, because in breaching the norms international stability may be threatened. In short, it follows that if a non-state entity is going to use force on a global scale, the maintenance of global peace and security demand that the U.N. conflict management regime should govern that group’s behavior as a matter of law.

Even if one were to dismiss each of the above arguments that the Charter’s provisions should bind terrorist groups as a matter of law, there is no question that a state that is attacked by a terrorist group is bound by the Charter’s norms both as a matter of conventional and customary law, because the language of Article 51 does not restrict against whom the inherent right of self-defense may be exercised.[108] Thus, a state may rightfully exercise self-defense in response to an armed terrorist attack as long as the response comports with the Charter’s strictures and relevant customary international law norms. In sum, even if international norms do not constrain the actions of terrorist groups as a matter of law with regard to the use of force, they do define the scope of actions that a state may take in response to an armed attack by a non-state entity.

Finally, one last argument pertaining to the applicability of the Charter requires attention. One could argue that because the Charter’s language suggests that it only regulates the use of force between states, the use of armed force against terrorists is impermissible in that any use of force not sanctioned by the Charter is unauthorized.[109] Such a reading of the Charter is unduly narrow in both a pragmatic and normative sense. As a practical matter, construing the Charter in such a manner would effectively leave a state helpless by denying it the right of self-defense against an armed attack by a terrorist organization.[110] This would be tantamount to unilateral disarmament by all sovereign states against acts of terrorism.[111] Under this theory, a state could only rightfully respond to an armed attack by another state, while a terror group would, in essence, be granted immunity from all acts of counter force. This outcome would fly in the face of the Charter’s purpose “to maintain international peace and security” and to “bring about by peaceful means, . . . adjustment or settlement of international disputes or situations which might lead to a breach of the peace.”[112] Moreover, to interpret Article 51 in such manner ignores the fact that the inherent right of self-defense, which is also a matter of customary international law, exists independently of the Charter.[113] Thus, even if the Charter somehow deprived a state of the ability to defend itself against a terrorist attack, a state still has that right as a matter of extant customary law.[114] Given the pragmatic considerations and the purpose of the Charter, the better answer is that the use of force regime applies to hostilities involving terrorist networks.

2. Customary International Law: Apart from whether the use of force paradigm as set forth in the Charter applies to conflicts with terrorist groups, question of whether extant rules of customary law govern hostilities with such groups remains.[115] The foregoing anlaysis indicates that customary law should apply to conflicts with terrorist groups for the same reasons that the Charter applies to such conflicts as a matter of customary law. Customary international law should only apply to the extent that it differs from the Charter. Nonetheless, conflicts between state and non-state actors should still be bound by extant customary law.

C. Applying the Jus Ad Bellum to the Strike in Yemen

In that the conflict between the U.S. and al-Qaeda is governed by the jus ad bellum pursuant to conventional and customary international law, at least to the extent that the U.S. is bound by these international use of force norms, the legality of the Yemen attack must be viewed through the prism of these two bodies of law. Specifically, whether the U.S. had a right to use self-help after September 11, and whether the strike in Yemen last November was consistent with that right.[116]

Whether the U.S. had a right to self-defense under the U.N. Charter depends on whether the U.S. sustained an “armed attack” and on the subsequent actions of the Security Council. There can be little doubt that the terrorist attacks carried out by al-Qaeda on September 11 were of sufficient gravity both quantitatively and qualitatively to constitute an armed attack as envisaged by the Charter.[117] More people died on the morning of September 11[118] than died during the attack on Pearl Harbor.[119] In addition to the loss of life, the damage to the American economy has been appraised at over $630 billion through 2003.[120] Not only was the strike an act of aggression against civilians and civilian property, but the attack on the Pentagon, the heart of the U.S. military command structure, was unequivocally an attack against the state.[121] Even if the hijacking of four planes on the morning of September 11 was viewed collectively as a single event, it was but one act of aggression in a long line of attacks by al-Qaeda against Americans and American interests worldwide.[122] The totality of these attacks support the claim that as of September 12 the U.S. justifiably concluded, as both a de facto and a de jure matter, that it was the victim of an armed attack that triggered the inherent right to exercise self-defense.[123]

Once international law vested the U.S. with the right to use self-help, the U.S. retained the right, unless the U.N. Security Council took “measures necessary to maintain international peace and security.”[124] On September 12, the Council passed a resolution condemning the attacks, calling upon states to combat terrorism, and “[r]ecognizing the inherent right of individual or collective self-defence [sic] in accordance with the Charter.”[125] Later that month, the Council reaffirmed the inherent right of self-defense and acknowledged “the need to combat by all means, in accordance with the Charter of the United Nations, threats to international peace and security caused by terrorist acts.”[126] The same resolution declared under Chapter VII that the “acts, methods, and practices of terrorism are contrary to the purposes and principles of the United Nations . . . .”[127] While the U.N. did not explicitly authorize military action, it did not need to. Action by the Security Council is not a condition precedent to the use of self-help. Rather, one may exercise self-help until the Council takes action. In this case, the Council’s repeated reaffirmation of the inherent right to self-defense could be reasonably construed as implicitly recognizing the right of the U.S. to use self-help.[128] Moreover, the Security Council failed to renounce the use of self-help even after the U.S. notified the Council that it had, “[i]n accordance with Article 51 of the Charter of the United Nations, . . . initiated actions in the exercise of its inherent right of individual and collective self-defence [sic] following the armed attacks that were carried out against the United States on 11 September 2001.”[129] If the U.N. had disapproved of the actions taken by the U.S., it could have expressed its displeasure by voting to condemn such action, or it could have formally terminated Washington’s right to use self-help by taking “measures” as contemplated by the Charter. The Council has done neither.

Although the U.S. had a right under the U.N. Charter to respond with force, we must also examine whether such a right existed as a matter of customary international law. Customary international law sanctions the use of counter force to the extent allowed by the Charter, provided that the precepts of necessity and proportionality are satisfied.[130] As required by the doctrine of necessity, the United States did not respond with force until it had explored peaceful options in response to the September 11 attacks.[131] Although it was not possible to seek a negotiated settlement with al-Qaeda because the terrorist group is a clandestine organization with no formal legal representatives, the U.S. government attempted to avert conflict by pursuing the only other seemingly viable diplomatic option when it called upon the Taliban government to produce Osama bin Laden and other al-Qaeda leaders believed to be responsible for September 11th.[132] The Taliban refused to negotiate, at times seeming more eager to go to war than the U.S.[133] After nearly four weeks, Washington concluded that given the threat of another terrorist attack by al-Qaeda, the only viable option was to use military force. Instead of using force, the U.S. could have, as a matter of policy, continued to pursue a diplomatic solution, or chosen not to respond at all to the September attacks, but policy considerations do not dictate legal considerations.[134] An attacked state does not need to wait indefinitely before exercising a right to use counter force. Indeed, a prolonged delay in responding to a terrorist attack might jeopardize a state’s right to respond.[135] It was only after the U.S. made feasible overtures to peacefully resolve the situation with al-Qaeda through the Taliban that it chose to exercise self-help. Thus, the initial application of self-defense was consistent with the principle of military necessity.

Whether the attack in Yemen in November 2002 that transpired fourteen months after the attacks in the U.S. was warranted depends on whether there existed a continued military necessity, as required by the jus ad bellum, that justified the right to self-defense. Recall that necessity is not a temporal limit on the right to use counter force.[136] The defending party may use responsive force until the enemy is defeated. On November 3, 2002, the day of the Predator attack, the al-Qaeda organization was still operational. Its leadership had not surrendered nor been defeated. According to a recent statement by President Bush, about one-half of the al-Qaeda leadership has either been captured or killed.[137] While the exact number of al-Qaeda leaders captured or killed in November 2002 is unknown, it follows that far fewer leaders had been captured or killed in November 2002 than today. Moreover, this terrorist group has continually conducted terrorist operations since September 11th,[138] and recent statements by Osama bin Laden suggest that the organization still poses a threat.[139] Although these recent statements cannot justify the existence of military necessity as of the date of the Predator attack, they do evince the continued viability of the al-Qaeda organization since September 11, 2001. It follows then that al-Qaeda still posed a threat to the U.S. in November 2002. Thus, it was reasonable for the U.S. to conclude in November 2002 that military necessity, as required by the jus ad bellum, justified the use of counter force against the six al-Qaeda members found in Yemen.[140]

Finally, customary law mandates that the U.S. military response is proportionate to the on-going threat of force posed by al-Qaeda. The concept of proportionality, which is based upon a standard of reasonableness, allows the U.S. to use whatever force it deems necessary to defeat al-Qaeda, provided that the force is proportionate to the nature of the threat.[141] Because proportionality is not a mathematical calculation requiring exact symmetry, the U.S. response to September 11 is not limited to the nature and type of unlawful force initially used by al-Qaeda.[142] By all accounts, the U.S. response has been proportionate. The U.S. has used conventional military forces to search for Osama bin Laden and to destroy forces loyal to the al-Qaeda leader, in addition to finding suspected terror training camps and mountain hideouts. In light of the threat posed by the terrorist organization, the responsive force used by the U.S. cannot be said to be disproportionate.

The strategic use of special forces and advanced aircraft against terrorists is not a disproportionate use of force. Such a suggestion fails to understand the concept of proportionality since proportionality does not limit the means of the military response. Moreover, the suggestion that the U.S. response is asymmetrical in that there has been a loss of innocent life and damage to civilian property is equally without merit. It is unfortunate that protected persons have lost their lives in the war in Afghanistan. However, there is no question that al-Qaeda and its sympathizers were the target of U.S. actions, not the state of Afghanistan or the Afghan people.[143] Equally as important is that the quality of life for most Afghans has improved, and the country’s long-term prospects continue to mature as it recovers from years of Taliban rule.[144] Furthermore, if one considers the cost to the economies of both countries, there is no comparison between the financial losses suffered by the U.S., estimated at well over $600 billion, and the economic impact borne by Afghanistan.[145] Although proportionality is not based upon a simple dollar-for-dollar comparison, the point is that the actions of the U.S. have not been disproportionate, especially given the detriment to the U.S. economy. In short, considering the loss of life on September 11, the economic impact suffered by the U.S., and the continuing threat posed by al-Qaeda, it cannot be said that the U.S. response to September 11 has been disproportionate.[146]

To summarize, the use of force by the U.S. after September 11, and specifically on November 3, 2002, comports with the jus ad bellum in that the U.S. response has been consistent with the strictures of the U.N. Charter and customary law. The U.S. resorted to force only after it sustained an armed attack, and only after the matter was brought to the attention of the Security Council, which gave its imprimatur to the use of self-help. Furthermore, the use of force was justified by military necessity, in light of the threat posed by al-Qaeda and the unsuccessful efforts to avoid confrontation. In addition, the U.S. response has been proportionate to the perceived threat, in that the U.S. has sought to limit its actions to only those persons believed to belong to al-Qaeda, and the practical observation that many senior al-Qaeda leaders remain at large. It was in this context that the targeting of the suspected terrorists in Yemen was consistent with the jus ad bellum.

IV. The Jus in Bello and the Strike in Yemen

Although the jus ad bellum supports the right of the U.S. to continue to exercise self-defense in face of the perpetual terrorist threat after September 11, the legality of the attack on the six suspected al-Qaeda members under international law must also be viewed through the lens of the jus in bello—whether the means of force employed was consistent with the laws of war.[147] The jus in bello forms the basis of what is known as the law of armed conflict (LOAC) and more generally, humanitarian law, which is founded upon the customs and laws of war that have developed over the centuries.

A. The Law of Armed Conflict: The law of armed conflict is a body of international customary and treaty law that governs how force may be used during a military conflict. The purpose of LOAC is to make war as humane as possible by limiting the permissible scope of warfare.[148] Restrictions on the use of force are designed to minimize the effects of war on belligerents and non-belligerents alike. It might seem anomalous that a legal regime would seek to impose a set of rules upon the conduct of warfare. After all, if the goal in combat is to kill the enemy,[149] efforts to regulate hostilities might seem superfluous and inconsistent with that objective. However, it has been widely recognized since Sun Tzu in the fourth century B.C. that the goal in war is to defeat the enemy, not to destroy the enemy.[150] While pursuing the former may result in the latter, the objective of war is not to annihilate the adversary.[151] War is not violence for the sake of violence, but the application of military force necessary to bring about the submission of the enemy.[152] This concept operates on the premise that war has limits.[153] By placing limitations on the conduct of hostilities, the law of war endeavors to relativize the inherent tension between violence on the battlefield and the interest of humanity so that armed conflict does not degenerate into savagery.[154] Thus, it is a well-accepted international convention that military contests must be fought within the confines of generally recognized standards, with the goal of subduing the enemy with as little destruction as possible.[155]

1. General Principles: Fundamental to the notion of limited war is the concept of military necessity.[156] In the context of the jus in bello, military necessity requires that force may only be used against persons or objects contributing to an opponent’s war effort, whose total or partial destruction is expected to contribute to the successful conclusion of hostilities.[157] Professor L.C. Green put it succinctly:

The purpose of armed conflict is to defeat the adverse party. The law of armed conflict only permits such actions as are imperative for this purpose and forbids acts which go beyond this and cause injury to persons or damage to property not essential to achieving this end.[158]

In application, military necessity dictates what objects may legitimately be targeted.[159] By placing restrictions on how force may be used, military necessity diminishes the effects of war on both combatants and noncombatants alike.[160]

Central to the concept of military necessity are the principles of discrimination and proportionality, which prohibit the use of force in a wanton and indiscriminate manner.[161] Specifically, the concept of discrimination dictates who and what may lawfully be targeted. If efforts to reduce the horrors of war are going to succeed, it follows that force should only be used against those persons and objects actively engaged in the opponent’s war effort.[162] Thus, the law distinguishes between civilians and soldiers, and requires that force be used in a discriminate manner only against legitimate targets.

Proportionality demands that force is used in a manner to minimize the collateral damage to civilian persons and property.[163] It requires “weighing the interests arising from the success of the operation against the possible harmful effects upon protected persons or objects on the other.”[164] Stated differently, the gain sought from accomplishing the military objective must be balanced against the probable damage to noncombatants. Only if the well-being of protected persons or property is implicated is the concept of proportionality relevant to the battlefield. Moreover, proportionality isnot based upon a mathematical formula whereby the degree of responsive force is limited to the amount of force used by the aggressor. The concept does not require that counter force be limited to a lex talionis or an “in-kind” response.[165] If an opponent chooses to undertake offensive military action using only infantry soldiers, the defending force may use whatever means it has at its disposal, e.g., tanks, airplanes, etc., in repelling the attack; it is not limited to responding with its own foot soldiers. For example, it is equally lawful to target an enemy combatant with a M1A1 tank firing a 120 mm shell as it is with an M16 rifle firing a 5.56 mm round.[166] However, it would be unlawful to raze a village of 500 civilians to destroy a single enemy sniper.[167] A soldier may target the enemy with whatever means at his disposal, provided that he takes into account the possibility of collateral injury to civilians.

Although the aforementioned concepts limit the permissible scope of warfare, they are not inconsistent with effective war fighting. Quite the contrary, the jus in bello complements and supports "the principles of warfare embodied in the military concepts of objective, mass, economy of force, surprise, and security." [168] A military organization has finite resources. The supplies of both men and material are finite. Those resources must be used in the most effective and efficient manner. A commander would therefore only want to expend ordinance on targets of military value rather than objects with no military significance. It would make little sense to target a civilian, who poses no threat and does not contribute to an opponent’s war effort, as opposed to an enemy soldier or military base. Thus, it behooves military personnel to follow the fundamental tenets of the laws and customs of war because, if nothing else, notions of limited warfare are also consistent with good military practices.

2. Conventional Law: Battlefield customs have existed in one form or other since feudal times, but it was only in the mid to late nineteenth century that modern efforts to codify and refine the customary laws of war began. Over the past 140 years, there have been many attempts to establish positive law based upon the notions of limited warfare.[169] The first modern comprehensive code of war was drafted by Dr. Francis Lieber during the American Civil War.[170] Although the Lieber Code was promulgated for the benefit of Union forces, it served as a prototype for similar codes that were introduced in several countries between 1870 and 1893,[171] and continued to serve as “the foundation for much of the law of war as it was to exist over the next century, including World War II.”[172]

(a) The Hague Conventions and the Definition of Combatants: About the same time that the Lieber Code was introduced, a desire developed among European powers to regulate the use of modern armaments.[173]&nb