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Action Against Host States of Terrorist Groups

Abstract and Keywords

This chapter examines the problems that could arise when a state invokes self-defence to justify action against terrorist groups in another state. It first considers indirect armed attack against armed groups and the controversy surrounding the use of self-defence where armed groups are controlled by a foreign state, with particular reference to the International Court of Justice (ICJ) jurisprudence. It then discusses the possibility that an armed attack could occur, permitting a forcible response in the context of international law, without attribution to a state by citing the Nicaragua case in which the ICJ pronounced that self-defence is permissible against a host state in effective control of an armed group. The chapter also looks at the case of Afghanistan and its relationship to Al Qaeda as an example of a state’s claims of self-defence against terrorism.

Keywords: self-defence, terrorist group, armed attack, armed group, International Court of Justice, international law, Nicaragua, Afghanistan, Al Qaeda, terrorism

I. Introduction

Article 51 of the UN Charter does not indicate what constitutes an armed attack, or who can carry one out. It preserves the inherent right of self-defence in the case of an ‘armed attack’ per se, and not in relation to ‘any particular kind of attacker’.1 Self-defence may have tended to be used in the context of attacks by one state against another, but ‘there is no a priori reason why the term should be so confined’.2 Given the emergence of non-state actors capable of launching significant attacks abroad, the ability of target states to respond lawfully against such armed groups and states in which they are located is an important question, which has attracted widespread attention since the 11 September 2001 terrorist attacks. It would be a mistake, however, to believe that it had received little consideration before then.3 In 1963, Brownlie argued that ‘a co-ordinated (p. 721) and general campaign by powerful bands of irregulars, with obvious or easily proven complicity of the government of a state from which they operate, would constitute an “armed attack”’,4 and that, ‘In so far as there is a use of force by forces controlled by a foreign state, this may be met by lawful measures of self-defence’.5 However, the precise scope and extent of such defensive action is complex. With considerable foresight, Brownlie cautioned that ‘delicate problems’ could arise in such circumstances,6 and it is to these problems that we now turn.

II. Indirect Attack: State Control and Attribution

Action against armed groups is not a recent phenomenon—a (relatively small) number of states had consistently asserted the right to respond forcibly to such attacks over many years.7 Strikes tended to be limited to terrorist bases within host states, with some level of host state responsibility asserted, whilst the ‘self-defence’ claimed more often closely resembled armed reprisals. International reaction was mixed at best.8 Thus, Israel’s 1968 strike on Beirut airport in response to attacks by Arab groups within Lebanon was condemned unanimously by the Security Council,9 whereas US strikes on Al Qaeda targets in Afghanistan and Sudan in 1998, (p. 722) following terrorist attacks on its embassies in Kenya and Tanzania, were received more favourably.10

Some clarity was provided in the Nicaragua case, where the International Court of Justice (ICJ) confirmed that attacks need not be carried out by a state’s regular armed forces to trigger the right of self-defence. Relying on the General Assembly’s Definition of Aggression,11 it held that ‘armed attack’ for the purposes of self-defence included:

not merely action by regular armed forces across an international border, but also ‘the sending by or on behalf of a State of armed bands, groups, irregulars or mercenaries, which carry out acts of armed force against another State of such gravity as to amount to’ (inter alia) an actual armed attack conducted by regular forces, ‘or its substantial involvement therein’.12

Given that ‘states may not evade responsibility…when they, instead of acting through their own officials, use groups of individuals to undertake actions that are intended to damage…other states’,13 the Court’s use of the Definition of Aggression to cover indirect armed attack seems appropriate. It continued, however, to set an exacting threshold for attribution, finding the provision of weapons or of logistical or other support to be insufficient,14 and insisting that an armed attack (and hence self-defence) required ‘effective control’ of military operations on the part of the state.15

Equating ‘substantial involvement’ with ‘effective control’ was controversial, and the Court was not unanimous in its approach. Judge Schwebel found it too restrictive, and a departure from ‘accepted—and desirable—law’,16 whilst Judge Jennings believed that assistance falling short of control could, in combination with additional involvement, form an important element of armed attack: ‘to say that the provision of arms, coupled with “logistical or other support” is not armed attack is going much too far’.17 Nonetheless, the judgment echoed Brownlie’s support for self-defence where armed groups are controlled by a foreign state.

The International Criminal Tribunal for the former Yugoslavia (ICTY) subsequently used an alternative test to determine when armed forces act on behalf of (p. 723) a state. Distinguishing between the activities of individuals and those of organized armed groups, it held that attribution could be demonstrated in the latter case where a state exercises ‘overall control’ of the group as a whole.18 This slightly lower threshold is crossed where a state equips and finances the armed group, and assists in the coordination or planning of its activities. Nevertheless, it still requires more than mere assistance, providing a territorial base, or condoning its actions.19

Although it has been suggested that the ‘overall control’ test better reflects state practice and is more appropriate in the context of international terrorism,20 subsequent ICJ jurisprudence has seen the Court entrench its Nicaragua approach. Thus, in the Wall advisory opinion, the Court simply held that Article 51 recognizes the right of self-defence ‘in the case of armed attack by one State against another State’ and that, since Israel had not asserted the imputability of attacks launched from the West Bank to another state, self-defence was not relevant.21 Similarly, in the Armed Activities case, it held that Uganda had failed to prove the necessary involvement of the DRC in the activities of Allied Democratic Forces (ADF) and that, consequently, self-defence was not available as the attacks ‘did not emanate from armed bands or irregulars sent by the DRC or on behalf of the DRC, within the sense of…resolution 3314’.22 Neither case discussed the ‘overall control’ test, whilst the Court firmly dismissed its relevance in the Bosnia Genocide case.23

The clarity provided by Nicaragua (namely, that self-defence is permissible against a host state in effective control of an armed group) is, however, of limited value. First, both the Nicaragua and Armed Activities cases concerned defensive action against the host state itself, rather than against armed groups located therein. In such circumstances, it is ‘far less incredible’ that the ICJ required attribution of the attacks to the state against which force was being used,24 but this fails to address the more common (and more difficult) situation where force is limited to terrorist (p. 724) targets. Secondly, it fails to appreciate that effective control is likely to be difficult to demonstrate:

How could one prove that a particular terrorist group has acted upon instructions or directions or under the specific control of a state in such a manner as to imply that the state has…directed the perpetration of individual terrorist actions? The hidden nature of those groups, their being divided up into small and closely-knit units, the secretive contacts of officials of some specific states with terrorist groups, all this would make it virtually impossible…25

Far more likely, but not yet addressed by the ICJ, is that host state involvement comprises support for armed groups falling short of control, or else an inability to prevent attacks from its territory.

III. State Involvement Short of Control

It seems unclear whether, prior to 9/11, international law accepted that an armed attack could occur, permitting a forcible response, without attribution to a state. The international response to Operation Enduring Freedom (as a lawful exercise of self-defence), and its impact on the jus ad bellum is therefore important—and pivotal is the nature of the relationship between Al Qaeda and Afghanistan’s governing Taliban regime.

It was to be expected that Security Council Resolution 1368, adopted the day after 9/11, condemned the attacks. Perhaps more surprising was that, without any evidence as to the perpetrators and the extent of any state involvement, it also recognized the inherent right of self-defence in accordance with the UN Charter.26 Granted, it refers to the attacks as a ‘threat to international peace and security’ rather than an ‘armed attack’ per se, but the terms are not mutually exclusive.27 (p. 725) Furthermore, whilst it has been argued that the Security Council did not ‘recognize the right of self-defence to act against private actors without attribution to a state, but only generally reaffirmed the right of self-defence irrespective of context’,28 Resolution 1368 (2001) cannot sensibly be considered independently from the 9/11 paradigm. As such, it is difficult to escape the conclusion that the events of 9/11 were considered an armed attack in the context of Article 51,29 and that, moreover, ‘those responsible for aiding, supporting or harbouring the perpetrators, organizers and sponsors of these acts’ were to be ‘held accountable’.30 To the extent that this envisaged forcible action against a state ‘harbouring’ terrorists but not controlling their activities as per Nicaragua, it would seem to have exceeded the parameters of the jus ad bellum as accepted at the time.31 This was the US view, however,32 and the response launched on 7 October 2001, based explicitly on self-defence,33 struck both Al Qaeda and Taliban targets.

(p. 726) Complicity between Al Qaeda and the Taliban seemed certain, as did Afghanistan’s failure to ‘refrain from organizing, instigating, assisting or participating in…terrorist acts in another State or acquiescing in organized activities within its territory directed towards the commission of such acts when the acts…involve a threat or use of force’.34 This provision relates to the interpretation of Article 2(4), however, and it is an armed attack rather than an unlawful use of force, that triggers the right of self-defence.35 Three options therefore remain. The first is that Afghanistan was seen as responsible for 9/11 through its effective control of Al Qaeda. This seemed unlikely.36 Although the UK asserted that the attacks were only possible due to Al Qaeda’s ‘close alliance with the Taleban regime’,37 neither the UK nor the US suggested that it was subject to Afghan control.

Secondly, is that Afghanistan was deemed responsible for the attacks, and susceptible to defensive measures, on some other ground—most likely that its refusal to surrender Osama bin Laden to the US (or any suitable third state), to instigate its own investigation, or to close Al Qaeda training camps, represented an official endorsement of Al Qaeda’s activities and adoption of these as its own, as per the Tehran Hostages case and Article 11 of the International Law Commission’s (ILC’s) Articles on State Responsibility.38 The Security Council had called for Bin Laden’s surrender and the closure of all terrorist training facilities in Afghanistan,39 and the Taliban’s failure to comply may have represented ‘encouragement and assistance’—especially after Al Qaeda attacks on US embassies in 1999 and the USS Cole in 2000, when it was ‘foreseeable…that further actions would take place…controlled by (p. 727) Osama bin Laden and his associates from bases on the territory of Afghanistan’.40 The UN Secretary-General’s Personal Representative had even ‘exhorted the Taliban to hand over Bin Laden in compliance with [Security Council resolutions], and repeatedly spelled out the consequences that were likely to ensue from their continued refusal to do so’.41 Nonetheless, it was difficult to evidence Taliban approval for 9/11, ‘Nor could they perpetuate the acts of al Qaeda members in the same way as the Tehran Hostages Case’.42 Afghanistan’s adoption of Al Qaeda’s conduct as its own was, therefore, ‘questionable’.43

The final option is that the response was prima facie inconsistent with the prevailing rules.44 Given the difficulty in placing Operation Enduring Freedom within the Nicaragua framework, and yet virtually universal approval (based upon acceptance that the relationship between Al Qaeda and the Taliban exposed the latter to forcible measures),45 it may have reflected a move towards more flexibility regarding the state involvement necessary to constitute an armed attack. This would have been a significant development, and arguments to that effect were certainly common. Schmitt, for example, believed that ‘Without any doubt, the degree of support necessary to constitute an armed attack has dropped precipitously’,46 whilst numerous commentators suggested that the level of support required had, almost overnight, become that of ‘harbouring’ the group responsible.47 Cassese suggested that a broad spectrum of situations and varying levels of control or other involvement should (p. 728) be considered on a case-by-case basis, and that ‘the training, moving, lodging, and equipping of an insurgent or terrorist army, or simply giving sanctuary to rebels or terrorists…should engage the State’s responsibility for attacks’, whereas lesser forms of acquiescence should not.48 Similarly, the 2002 Commentary on the UN Charter saw the Nicaragua test as inadequate to protect states from indirect attack, suggesting that the extent to which state support has ‘enabled private groups to commit private acts of military force which, committed by a State, have to be qualified as “armed attack”’ should be decisive.49

Consistent with such an approach, Israel has been keen to claim the right to respond in self-defence against Hezbollah attacks launched from Lebanon. Asserting that Hezbollah was being harboured by Lebanon (and Syria), and that it was receiving support from those states (as well as from Iran), Israel clearly stopped short of claiming that the Nicaragua threshold had been crossed, and that Hezbollah was acting on behalf of, or controlled by, Lebanon. Nonetheless, it argued that without ‘financial, political and logistical support [from Syria, Lebanon and Iran], including the supply of weapons’, Hezbollah’s attacks would be impossible.50 Given that this was precisely the type of support envisaged by Resolution 1373 (2001) (which reaffirmed the right of self-defence in the context of terrorist attacks), Israel explicitly justified its actions as self-defence.51

When, following a 2003 Islamic Jihad terrorist attack, Israel extended its military operations beyond Lebanon into Syria, striking a terrorist base north-west of Damascus,52 Syria was accused of complicity by providing ‘encouragement, safe harbour, training facilities and logistical support’.53 Again referring to Resolution 1373 (2001), Israel claimed that its ‘measured’ response was ‘a clear act of self-defence in accordance with Article 51’.54 It found little support in the Security Council. Only the US insisted that Syria was ‘on the wrong side in the war on terrorism’, and that (p. 729) it must ‘stop harbouring and supporting the groups that perpetrate terrorist acts’,55 although condemnation was not framed in terms of a discussion of the lawfulness of action against armed groups and/or host states.56

The ICJ declined the opportunity to provide greater clarity in the Armed Activities case,57 where Uganda characterized its actions against the DRC as lawful self-defence, triggered by the support of the DRC for, as evidenced by its tolerance of, the activities of the ADF.58 Instead, the Court simply reaffirmed its Nicaragua judgment, holding that the ADF had not been sent ‘by or on behalf of’ DRC—rejecting, at least implicitly, the notion that tolerance of armed groups by a state triggers self-defence.59 The longer term implications of Operation Enduring Freedom are therefore unclear and, by 2005, suggestions of rapid developments in customary law were treated more cautiously. Cassese, for example, argued that what may at the time have appeared to indicate widespread acceptance of a broader right of self-defence had been ‘motivated by the emotional reaction to the horrific terrorist action of 11 September, [and] may not amount to the consistent practice and opinio juris required for a customary change’.60

Nonetheless, continued reliance on the Nicaragua test seems unpalatable, in that the consequences are:

(1) a state may provide weapons, logistical support and safe haven to a terrorist group; (2) that group may then inflict violence of any level of gravity on another state, even with (p. 730) weapons of mass destruction; (3) the second state has no right to respond in self-defense against the first state because the first state’s provision of such assistance is not an ‘armed attack’ within the meaning of Article 51; and (4) the second state has no right to respond in self-defense against the terrorist group because its conduct cannot be imputed to the first state, absent a showing that the first state ‘sent’ the terrorist group on its mission.61

As Murphy concludes, ‘Such a legal construct, if intended, seems unlikely to endure’.62 It is suggested that it has not—although it is, admittedly, disappointing that the Court was unable to assess the legality of a Ugandan response limited to proportionate strikes against ADF, rather than DRC, targets.

IV. Absence of Attribution: Failure/Inability to Prevent Attacks

Beyond the question of state support for armed groups operating from their territory, and a consequent unwillingness to prevent their attacks as required by international law, it is also possible that armed groups are free to launch cross-border attacks due to the host state’s lack of control over the entirety of its territory—and hence an inability, rather than an unwillingness, to prevent the attacks. This is clearly yet further removed from the Nicaragua threshold, in that the host state does not condone the group’s activities, let alone direct or control them. In the Wall advisory opinion, however, Judges Kooijmans and Buergenthal saw Resolutions 1368 (2001) and 1373 (2001) as demonstrating a new approach, recognizing the right to respond in self-defence without requiring that an armed attack be imputed to another state.63

As such, attribution as per Nicaragua would no longer be necessary for an armed attack to occur. The host state would not be responsible for the attack, and hence could not be targeted in response—but its inability to prevent terrorist attacks would leave its territorial integrity susceptible to ‘breach’ by the target state, with defensive action limited to terrorist targets.64 Yet again, Brownlie foresaw this possibility in 1963, although cautioning that the legitimacy of such a response must be based on (p. 731) ‘principle and policy since the legal materials relating to self-defence in international law contemplate action against states only’.65

It may well be, however, that at least one impact of 9/11 has been to permit states to contemplate defensive action against armed groups. After all, 9/11 clearly demonstrated the capacity of terrorists to cause significant damage, comparable to more ‘traditional’ attacks by regular armed forces, even without the control or complicity of any state.66 In the light of this, it would be a ‘strange formalism which regarded the right to take military action against those who caused or threatened such consequences as dependent upon whether their acts could somehow be imputed to a state’.67 Indeed, to hold otherwise would make terrorists operating from a ‘failed state’ incapable of launching an armed attack in the context of Article 51, denying the target state a lawful defensive response.68 This is neither reasonable nor realistic. Instead, rather than require attribution to a state to constitute an armed attack, attribution should determine the permissible target(s) of a defensive response.69 Thus, an inability to prevent 9/11 would not have made Afghanistan responsible for an indirect armed attack, but it would have rendered lawful a forcible response by the US and its allies against Al Qaeda.70

This view has gained credence post-9/11 in the opinion of numerous commentators,71 and in state practice. Russia, for example, claimed the right to respond against Chechen rebels in Georgia on the basis that Georgia was unwilling and unable to prevent their incursions into Russian territory. Asserting that ‘responsibility for the consequences of the armed incursion [therefore lay] fully with the Georgian side’,72 (p. 732) Russia reserved ‘the right to act in accordance with Article 51’.73 Similarly, Uganda argued in Armed Activities that the DRC had been unable to control the whole of its territory so as to prevent insurgent attacks, and in favour of a ‘standard of responsibility, according to which a failure to control the activities of armed bands, creates a susceptibility to action in self-defence’.74 The ICJ accepted that there had been a lack of control over the activities of rebels in the border region but, in the context of Uganda’s response against the DRC, held that this was not ‘tantamount to “tolerating” or “acquiescing” in their activities’, even if this lower standard was sufficient for attribution, and thereby constituted neither unlawful intervention in, nor armed attack against, Uganda.75

Judge Kooijmans agreed that an inability to control the activities of armed bands did not result in attribution, but refused to accept that this ruled out self-defence altogether as the Court had not considered the lawful response to action by armed groups which, ‘“because of its scale and effects, would have been classified as an armed attack…had it been carried out by regular armed forces”…but [where] no involvement of the “host government” can be proved’.76 Reiterating that Article 51 was not limited to attacks by one state on another,77 and again influenced by Security Council Resolutions 1368 and 1373, he argued that:

If the activities of armed bands present on a State’s territory cannot be attributed to that State, the victim State is not the object of an armed attack by it. But if the attacks by the irregulars would, because of their scale and effects, have had to be classified as an armed attack had they been carried out by regular armed forces, there is nothing in the language of Article 51 …that prevents the victim State from exercising its inherent right of self-defence.78

Agreeing that terrorist acts can constitute armed attacks without attribution, Judge Simma believed that it ‘would be unreasonable to deny the attacked State the right to self-defence merely because there is no attacker State and the Charter does not require so’.79

By 2006, a group of leading British international lawyers adopted a set of principles outlining their view that ‘the right of States to defend themselves against ongoing attacks, even by private groups of non-state actors, is not generally questioned’, and that: (p. 733)

The right to use force in self-defence…is not dependent upon any prior breach of international law by the State in the territory of which defensive force is used.

Thus, where a State is unable or unwilling to assert control over a terrorist organization located in its territory, the State which is a victim of the terrorist attacks would, as a last resort, be permitted to act in self-defence against the terrorist organization in the State in which it is located.80

When, in the same year, Israel took further military action against Hezbollah targets in Lebanon,81 it again asserted that it was acting in self-defence and argued that responsibility lay with ‘Lebanon, from whose territory these acts have been launched into Israel’.82 Rather than claim active support or participation in the attacks, however, Israel asserted that Lebanon had been unable to exercise appropriate jurisdiction over its own territory due to ‘ineptitude and inaction’.83 Its response, limited to ‘Hizbollah strongholds, positions and infrastructure’,84 met with significant criticism (primarily for lack of proportionality),85 although the Security Council stressed that Lebanon had a responsibility to exercise effective control over its territory, preventing further Hezbollah attacks, and most Council members did accept that Israel had the right to take defensive action in the circumstances.86

Similarly, Turkish attacks on PKK targets in northern Iraq have received little to no international condemnation.87 At least since 2007, a clear legal justification for these actions has not been easily discerned,88 nor have these Turkish actions been reported to the Security Council as required by Article 51.89 Nonetheless, Turkey clearly did not consider the attacks imputable to Iraq,90 and the international community has (p. 734) done little to cast doubt upon the availability of self-defence in such circumstances. Indeed, whilst many states were equivocal in their response,91 the Dutch foreign minister asserted in 2008 that, ‘Kurdish attacks from Iraq have taken place on Turkish territory, and since the UN Security Council has not yet taken any measures against these attacks, Turkey can invoke the right of self-defence’.92 This position was reiterated, and supported by the US, following similar operations in 2011.93

V. Conclusion

As Judge Higgins explained, ‘nothing in the text of Article 51 …stipulates that self-defence is available only when an armed attack is made by a State. That qualification is rather a result of the Court so determining in [the Nicaragua case]’.94 The Nicaragua judgment has, however, been subjected to consistent criticism, and its continuing efficacy has been questioned.95 If the concept of self-defence is to retain any modern value, states must be permitted to defend themselves against armed attacks, irrespective of the perpetrators. As Lowe indicates, ‘Self-defence is an inherent right; and the right exists whenever one is attacked, whether by a State army or by an individual terrorist’.96 To suggest that states may not lawfully defend themselves because state control over, or substantial involvement in, the activities of armed groups cannot be demonstrated seems unfair, ‘lacks correspondence with the realities of international politics and, more importantly, cannot explain states’ overwhelming approval of the US action in Afghanistan’.97

(p. 735) The relationship between Afghanistan and Al Qaeda was probably unique in the context of an international system predicated on the superiority of states, and the 9/11 attacks were accordingly difficult to assess through the prevailing rules requiring effective control. Equally, support for the extension of military operations beyond Al Qaeda to the Taliban could probably be explained by reasons that were as political as they were legal.98 Nonetheless, bolstered by the effect of Security Council Resolutions 1368 and 1373, there does seem to be a trend towards accepting the possibility of lawful self-defence without attribution to the host state. A strict requirement to demonstrate imputability would, after all, severely limit the ability of states to take defensive action in a situation which is ‘per definitionem so urgent that it does not logically allow a state victim of an armed attack to wait to raise questions of responsibility’.99 State practice does, however, also tend to indicate that some responsibility on the part of the host state is still asserted—from harbouring or otherwise supporting/assisting the armed group in question to simply being unable to prevent its activities. Attribution of an armed attack to a state is, therefore, more relevant to the question of who may be targeted by the defensive response than to the question of whether the victim state has been subjected to an armed attack per se.

Armed action against armed groups where the host state cannot take preventive action certainly appears to meet the ‘necessity’ criteria for lawful self-defence in that, given the host state’s failure to control its own territory, there is no reasonable and/or effective alternative to the use of force.100 As such, a host state’s inability to take effective measures against armed groups operating from its territory is probably now tantamount to the level of involvement necessary to render action against those armed groups lawful. Clearly, then, a forcible response is equally necessary where the host state is, due to its tolerance of and support for the presence and activities of an armed group, unwilling, rather than unable, to prevent its military activities. Defensive action against the host state itself would, however, only be necessary where attribution is present and there has actually been an indirect armed attack by that state, acting through an armed group as per Nicaragua, or else where it actively resists lawful measures taken against armed groups on its territory.

(p. 736) The Nicaragua and Armed Activities cases both concerned action against host states, and it is important not to broaden their scope beyond reason. It must also be borne in mind that most claims of self-defence against terrorist attacks have asserted the right only against terrorist targets. Recent developments probably indicate the availability and acceptance of defensive measures against armed groups where the host state is unwilling or unable to prevent their activities, but to permit action against the host state in such situations would ‘too readily justify the robust use of military force [and]…set dangerous precedents’.101 International law does not do so.

Notes:

(1) Thomas Franck, ‘Terrorism and the Right of Self-Defense’ (2001) 95 American Journal of International Law 839, 840.

(2) Christopher Greenwood, ‘International Law and the “War Against Terrorism”’ (2002) 78 International Affairs 301, 307.

(3) The Caroline dispute, widely considered the locus classicus regarding self-defence in customary international law, concerned the activities of Canadian rebels, rather than regular state forces. See Greenwood, ‘International Law and the “War Against Terrorism”’, 308; Jordan J. Paust, ‘Use of Armed Force Against Terrorists in Afghanistan, Iraq, and Beyond’ (2002) 35 Cornell International Law Journal 533, 535; Derek Jinks, ‘Self-Defense in an Age of Terrorism’ (2003) Proceedings of the American Society of International Law 141, 146.

(4) Ian Brownlie, International Law and the Use of Force by States (Oxford: Oxford University Press, 1963), 279.

(5) Brownlie, International Law and the Use of Force by States, 372.

(6) Brownlie, International Law and the Use of Force by States, 372–3.

(7) Perhaps most extensively Israel, Portugal, South Africa, and the US. See Antonio Cassese, ‘Terrorism is Also Disrupting Some Crucial Legal Categories of International Law’ (2001) 12 European Journal of International Law 993, 996; Christine Gray, International Law and the Use of Force (3rd edn, Oxford: Oxford University Press, 2008), 195–8; Lindsay Moir, Reappraising the Resort to Force: International Law, Jus ad Bellum and the War on Terror (Oxford: Hart, 2010), 25–31; Tom Ruys and Sten Verhoeven, ‘Attacks by Private Actors and the Right of Self-Defence’ (2005) Journal of Conflict and Security Law 289, 292–6.

(8) Although condemnation or otherwise often hinged upon issues such as perceived responsibility for the attack, the proportionality of any response, armed struggles in the context of self-determination, etc, rather than discussion as to the scope of self-defence.

(9) SC Res 262 (1968), 31 Dec 1968. See also Gray, International Law and the Use of Force, 195; Richard A. Falk, ‘The Beirut Raid and the International Law of Retaliation’ (1969) 63 American Journal of International Law 415.

(10) Sean D. Murphy, ‘Contemporary Practice of the United States relating to International Law’ (1999) 93 American Journal of International Law 161; Gray, International Law and the Use of Force, 197.

(11) GA Res 3314 (XXIX), Definition of Aggression, 14 Dec 1974, para 3(g).

(12) Case Concerning Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. US), Merits, Judgment of 27 June 1986, ICJ Rep 1986, para 195.

(13) Antonio Cassese, ‘The Nicaragua and Tadić Tests Revisited in Light of the ICJ Judgment on Genocide in Bosnia’ (2007) 18 European Journal of International Law 649, 654.

(14) Nicaragua, Merits, para 195. It could, however, constitute a violation of Art 2(4).

(15) Nicaragua, Merits, para 115. No explanation was provided as to why this was so, nor reference to state practice or other authorities. See Cassese, ‘The Nicaragua and Tadić Tests Revisited’, 653.

(16) Nicaragua, Merits, Dissenting Opinion of Judge Schwebel, para 155. He argued, paras 162–71, that provision of ‘arms, munitions, other supplies, training, command-and-control facilities, sanctuary and lesser forms of assistance’ represented ‘substantial involvement’, and should permit an armed response in self-defence.

(17) Nicaragua, Merits, Dissenting Opinion of Judge Jennings, 528, 543.

(18) Prosecutor v. Tadić, Appeals Chamber Judgment of 15 July 1999, para 120.

(19) Tadić, Appeals Chamber Judgment, paras 130–1.

(20) Cassese, ‘The Nicaragua and Tadić Tests Revisited’, 657–63, 665–7.

(21) Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, 9 July 2004, ICJ Rep 2004, para 139. Clearly a higher threshold than ‘substantial involvement’, this position was described as ‘remarkable’, and contrary to Nicaragua and state practice. See Ruys and Verhoeven, ‘Attacks by Private Actors and the Right of Self-Defence’, 304–5; Christian Tams, ‘Light Treatment of a Complex Problem: The Law of Self-Defence in the Wall Case’ (2006) 16 European Journal of International Law 963, 978.

(22) Case Concerning Armed Activities on the Territory of the Congo (DRC v. Uganda), Judgment of 19 Dec 2005, ICJ Rep 2005, para 146.

(23) Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v. Serbia and Montenegro), Judgment of 26 Feb 2007, ICJ Rep 2007, paras 402–6. See Raphaël van Steenberghe, ‘Self-Defence in Response to Attacks by Non-State Actors in the Light of Recent State Practice: A Step Forward?’ (2010) 23 Leiden Journal of International Law 183, 195–6; and strong criticism of the Court’s approach by Cassese, ‘The Nicaragua and Tadić Tests Revisited’.

(24) Kimberley N. Trapp, ‘Back to Basics: Necessity, Proportionality, and the Right of Self-Defence Against Non-State Terrorist Actors’ (2007) 56 International and Comparative Law Quarterly 141, 142.

(25) Cassese, ‘The Nicaragua and Tadić Tests Revisited’, 666. See also Carsten Stahn, ‘International Law at a Crossroads? The Impact of September 11’ (2002) Zeitschrift für ausländisches öffentliches Recht und Völkerrecht 183, 219.

(26) SC Res 1373 (2001), 28 Sept 2001, reaffirmed the characterization of the attacks as a threat to international peace and security, recognized the right of self-defence and reiterated the duty upon all states to ‘refrain from organizing, instigating, assisting or participating in terrorist acts in another State or in acquiescing in organized activities within its territory directed towards the commission of such acts’.

(27) See Greenwood, ‘International Law and the “War Against Terrorism”’, 307, outlining that Iraq’s 1990 invasion of Kuwait—clearly an armed attack—was also referred to by the Security Council in the context of (a breach of) international peace and security.

(28) Jörg Kammerhofer, ‘The Armed Activities Case and Non-State Actors in Self-Defence Law’ (2007) 20 Leiden Journal of International Law 89, 99.

(29) Greenwood, ‘International Law and the “War Against Terrorism”’, 308; Franck, ‘Terrorism and the Right of Self-Defense’, 840.

(30) SC Res 1368 (2001), para 3. The US apparently considered this as authorization to use force. See William Taft, ‘International Law and the “War on Terror”: A Look Back’ (2009) Proceedings of the American Society of International Law 345, 352. Ralph Zacklin, ‘The United Nations Secretariat and the Use of Force in a Unipolar World’, Hersch Lauterpacht Memorial Lectures, Lecture III, University of Cambridge, 24 Jan 2008, available at <www.lcil.cam.ac.uk/Media/lectures/pdf/2008_Hersch_Lectures/2008_Lecture_3.pdf>, highlights concern by senior UN officials that Art 51 was being ‘distorted’ and that the Security Council ‘had acted in the emotion of the moment rather than with calm deliberation…instead of assuming a responsible position of leadership it had in effect provided the United States with a green light to take any action it deemed appropriate’.

(31) See eg Paust, ‘Use of Armed Force Against Terrorists in Afghanistan, Iraq, and Beyond’, 540: ‘Absent U.N. Security Council or regional organization authorization to use military force against a state that merely harbors terrorists or is unable to control misuse of its territory, and absent direct involvement by such state in a process of armed attack that triggers the right of self-defense…the use of military force against such a state would be impermissible’.

(32) President Bush stated that the US would make ‘no distinction between the terrorists who committed these acts and those who harbor them’ and, on 18 Sept, Congress authorized action against ‘those nations, organizations or persons [found to have] planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harboured such organizations or persons’. See ‘Address to the Nation on the Terrorist Attacks’ (11 Sept 2001), 37 Weekly Compilation of Presidential Documents 1301 (17 Sept 2001); ‘Authorization for Use of Military Force’, Public Law No 107–140, 115 Stat 224 (18 Sept 2001), para 2(a).

(33) The US informed the Security Council that it was acting pursuant to Art 51, and that the 9/11 attacks and ongoing threat from Al Qaeda resulted from ‘the decision of the Taliban regime to allow the parts of Afghanistan that it controls to be used by this organization as a base of operation’. See Letter dated 7 October 2001 from the Permanent Representative of the United States of America to the United Nations addressed to the President of the Security Council, S/2001/946 (7 Oct 2001). The UK indicated that it too was acting under Art 51 against ‘Usama Bin Laden’s Al-Qaeda terrorist organization and the Taliban regime that is supporting it’. See Letter dated 7 October 2001 from the Chargé d’Affaires a.i. of the Permanent Mission of the United Kingdom of Great Britain and Northern Ireland to the United Nations addressed to the President of the Security Council, S/2001/947 (7 Oct 2001).

(34) GA Res 2625 (XXV), Declaration on Principles of International Law Concerning Friendly Relations and Cooperation among States in Accordance with the Charter of the United Nations, 24 Oct 1970.

(35) Albrecht Randelzhofer, ‘Article 51’ in Bruno Simma et al (ed), The Charter of the United Nations: A Commentary (2nd edn, Oxford: Oxford University Press, 2002), vol I, 788, 790–2.

(36) It was suggested that the Taliban was more dependent upon Al Qaeda than vice versa. See Michael N. Schmitt, ‘Deconstructing October 7th: A Case Study in the Lawfulness of Counterterrorist Military Operations’ in Michael N. Schmitt and Gian Luca Beruto (eds), Terrorism and International Law: Challenges and Responses (Sanremo: International Institute of Humanitarian Law, 2003) 39, 45–6.

(37) UK Government, ‘Responsibility for the Terrorist Atrocities in the United States’, available at <http://www.number-10.gov.uk/output/page3682.asp>. Indeed, there was agreement that responsibility ‘had to be laid partly at the door of the Taliban Government’. See Peter Rowe, ‘Responses to Terror: The New “War”’ (2002) 3 Melbourne Journal of International Law 301, 307–8.

(38) United States Diplomatic and Consular Staff in Tehran (US v. Iran), Judgment of 24 May 1980, ICJ Rep 1980, paras 73–4; Annex to GA Res 56/83 (12 Dec 2001), International Law Commission Articles on Responsibility of States for Internationally Wrongful Acts (2001). See Sean D. Murphy, ‘Terrorism and the Concept of “Armed Attack” in Article 51 of the UN Charter’ (2002) 43 Harvard International Law Journal 41, 50–1.

(39) SC Res 1267 (1999), 15 Oct 1999, demanded that the Taliban ‘turn over Usama bin Laden without further delay to appropriate authorities in a country where he has been indicted, or to appropriate authorities in a country where he will be returned to such a country, or to appropriate authorities in a country where he will be arrested and effectively brought to justice’; SC Res 1333 (2000), 19 Dec 2000, repeated this, further demanding that the Taliban ‘close all camps where terrorists are trained within the territory under its control’.

(40) Rowe, ‘Responses to Terror’, 309.

(41) Report of the Secretary-General to the General Assembly and Security Council, The Situation in Afghanistan and its Implications for International Peace and Security, A/56/681–S/2001/1157 (6 Dec 2001), para 90. See also Taft, ‘International Law and the “War on Terror”’, 351.

(42) Rowe, ‘Responses to Terror’, 308.

(43) Stahn, ‘International Law at a Crossroads?’, 220–1.

(44) Paust, ‘Use of Armed Force Against Terrorists in Afghanistan, Iraq, and Beyond’, 542–3.

(45) See Malcom Shaw, ‘War View: Keep the Response Legal’, 9 Oct 2001, available at <http://news.bbc.co.uk/hi/english/uk/newsid_1587000/1587034.stm>, indicating that, ‘governments…around the globe’ found the responsibility of Afghanistan to have been ‘adequately demonstrated’. Antonio Cassese, International Law (2nd edn, Oxford: Oxford University Press, 2005), 474, suggested that ‘practically all states’ had accepted the legitimacy of action in response to the attacks based on Art 51. See also Gray, International Law and the Use of Force, 193; Sean D. Murphy, ‘Terrorist Attacks on the World Trade Center and Pentagon’ (2002) 96 American Journal of International Law 237, 248.

(46) Michael N. Schmitt, ‘The Legality of Operation Iraqi Freedom under International Law’ (2004) Journal of Military Ethics 82, 88. See also Michael N. Schmitt, ‘US Security Strategies: A Legal Assessment’ (2004) 27 Harvard Journal of Law and Public Policy 737, 762.

(47) See eg Ronli Sifris, ‘Operation Iraqi Freedom: United States v Iraq—The Legality of the War’ (2003) 4 Melbourne Journal of International Law 521, 534; Devika Hovell, ‘Chinks in the Armour: International Law, Terrorism and the Use of Force’ (2004) 27 University of New South Wales Law Journal 398, 414; Christian Henderson, ‘The Bush Doctrine: From Theory to Practice’ (2004) 9 Journal of Conflict and Security Law 3, 5; Ruys and Verhoeven, ‘Attacks by Private Actors and the Right of Self-Defence’, 319; Olivier Corten, ‘The Controversies over the Customary Prohibition on the Use of Force: A Methodological Debate’ (2006) 16 European Journal of International Law 803, 810; Cassese, ‘Terrorism is Also Disrupting Some Crucial Legal Categories of International Law’, 996–7; Christine Gray, ‘The Use of Force and the International Legal Order’ in Malcolm D. Evans (ed), International Law (2nd edn, Oxford: Oxford University Press, 2006), 589, 602.

(48) Cassese, International Law, 471–2.

(49) Randelzhofer, ‘Article 51’ in Simma et al, The Charter of the United Nations: A Commentary, 801: where a state ‘places its territory at the disposal of [an armed] group to train its members and to offer them a safe haven…it is hardly to be understood why this should be a lesser participation in the acts of the group than the mere sending of it. It is not adequate to exclude generally certain types of supporting terrorism from being qualified as “substantial involvement” and consequently “armed attack”.’

(50) Letter dated 10 April 2002 from the Chargé d’Affaires a.i. of the Permanent Mission of Israel to the United Nations addressed to the Secretary-General, A/56/913–S/2002/374.

(51) Letter dated 5 September 2002 from the Permanent Representative of Israel to the United Nations addressed to the Secretary-General, A/56/1032–S/2002/986; Letter dated 27 January 2003 from the Permanent Representative of Israel to the United Nations addressed to the Secretary-General, A/57/717–S/2003/96; Identical Letters dated 11 August 2003 from the Permanent Representative of Israel to the United Nations addressed to the Secretary-General and the President of the Security Council, A/57/857–S/2003/806.

(52) See discussion in Trapp, ‘Back to Basics’, 152–3; Gray, International Law and the Use of Force, 236–7.

(53) SCOR, 4836th mtg, S/PV.4836 (5 Oct 2003), 5–6.

(54) SCOR, 4836th mtg, S/PV.4836 (5 Oct 2003), 7.

(55) SCOR, 4836th mtg, S/PV.4836 (5 Oct 2003), 14. Pakistan, Spain, China, France, Bulgaria, Chile, Mexico, and Cameroon, SCOR, 4836th mtg, S/PV.4836 (5 Oct 2003), 8–11, 13, all agreed that the Israeli response violated international law; Mexico and Guinea suggested that it was an armed reprisal.

(56) The UK and Germany, SCOR, 4836th mtg, S/PV.4836 (5 Oct 2003), 9–10, made no reference to international law, simply describing Israel’s actions as ‘unacceptable’, whilst most members considered things in the broader context of the Middle East peace process.

(57) Armed Activities, Judgment, Separate Opinion of Judge Simma, para 11. Judge Kooijmans believed that, in refusing to consider the continuing relevance of Nicaragua, the Court had ‘missed the chance to fine-tune the position it took 20 years ago in spite of the explicit invitation by one of the Parties to do so’. See Armed Activities, Judgment, Separate Opinion of Judge Kooijmans, para 25; Dissenting Opinion of Judge Kateka, para 13.

(58) It argued that tolerance on the part of the DRC served to ‘generate legal responsibility’ such that the activities of the ADF represented ‘armed attacks for the purpose of Article 51’. See Counsel for Uganda, Oral Pleadings, CR 2005/7, 30, para 80. Counsel for the DRC countered that this was contrary to Nicaragua and therefore to ‘established principles’. See Oral Pleadings, CR 2005/12, 26, para 6.

(59) The ICJ in the Armed Activities case, at para 147, saw ‘no need to respond to the contentions of the Parties as to whether and under what conditions contemporary international law provides for a right of self-defence against large-scale attacks by irregular forces’ although, having decided that Uganda’s military action was not self-defence because ADF attacks could not be attributed to the DRC, it would seem to have resolved the issue. See also Separate Opinion of Judge Kooijmans, para 22.

(60) Cassese, International Law, 475. Gilbert Guillaume, ‘Terrorism and International Law’ (2004) 53 International and Comparative Law Quarterly 537, 547, also argued that ‘this evolution would amount to such a radical change in international law that it would require clearer practice and a more constant opinio juris’; whilst Gery Simpson, Great Powers and Outlaw States (Cambridge: Cambridge University Press, 2004), 335–6, suspected that any such ‘instant custom’ would ‘dissolve as quickly as it appeared’ when more expansive self-defence was claimed by other states.

(61) Sean D. Murphy, ‘Self-Defense and the Israeli Wall Advisory Opinion: An Ipse Dixit from the Court?’ (2005) 99 American Journal of International Law 62, 66.

(62) Murphy, ‘Self-Defense and the Israeli Wall Advisory Opinion’, 66.

(63) Wall, Advisory Opinion, Separate Opinion of Judge Kooijmans, para 35; Declaration of Judge Buergenthal, para 6.

(64) Kammerhofer, ‘The Armed Activities Case and Non-State Actors in Self-Defence Law’, 105; ‘The Chatham House Principles of International Law on the Use of Force in Self-Defence’ (2006) 55 International and Comparative Law Quarterly 963, 970.

(65) Brownlie, International Law and the Use of Force By States, 375.

(66) Greenwood, ‘International Law and the “War Against Terrorism”’, 307.

(67) Greenwood, ‘International Law and the “War Against Terrorism”’, 307.

(68) Stahn, ‘International Law at a Crossroads?’, 214–15.

(69) Jackson N. Maogoto, ‘War on the Enemy: Self-Defence and State-Sponsored Terrorism’ (2003) 4 Melbourne Journal of International Law 406, 431. Shaw similarly argued (‘War View: Keep the Response Legal’), that the 9/11 attacks could not ‘constitute anything other than an “armed attack”’, but ‘more difficult to answer is the question of responsibility’.

(70) Schmitt, ‘Deconstructing October 7th’, 45. Paust, ‘Use of Armed Force Against Terrorists in Afghanistan, Iraq, and Beyond’, 540, maintained that ‘unless the state is organizing, fomenting, directing, or otherwise directly participating in armed attacks by non-state terrorists, the use of military force against the state, as opposed to only the non-state terrorists, would be impermissible’ (emphasis added). Although the Taliban seemed unwilling rather than unable, limiting the response in this way would have avoided controversy in that, whilst the Taliban had indicated that it would ‘vigorously oppose any foreign forces entering its territory to root out Al-Qaida bases’, Taliban targets were attacked ‘before they had the chance to resist’. See Christopher Greenwood, ‘International Law and the Preemptive Use of Force: Afghanistan, Al-Qaida, and Iraq’ (2003) 4 San Diego Journal of International Law 7, 25; Schmitt, ‘US Security Strategies’, 760.

(71) See eg Angus Martyn, ‘The Right of Self-Defence under International Law—the Response to the Terrorist Attacks of 11 September’, Parliament of Australia Current Issues Brief No 8, 2001–02, 12 Feb 2002, available at <http://www.aph.gov.au/library/pubs/CIB/2001-02/02cib08.htm>: ‘terrorist groups with the means to reach across international borders to inflict significant damage…must represent the sort of threat against which self-defence is legitimate if the doctrine is to have any practical contemporary value’; Guillaume, ‘Terrorism and International Law’, 546.

(72) Letter dated 31 July 2002 from the Chargé d’Affaires a.i. of the Permanent Mission of the Russian Federation to the United Nations addressed to the Secretary-General, A/57/269–S/2002/854.

(73) Letter dated 11 September 2002 from the Permanent Representative of the Russian Federation to the United Nations addressed to the Secretary-General, S/2002/1012. US opposition to the Russian position should, however, be noted for its potential impact on the development of a customary rule. See Gray, International Law and the Use of Force, 230–1.

(74) Armed Activities, Oral Pleadings, Counsel for Uganda, para 80.

(75) Wall, Advisory Opinion, paras 300–1.

(76) Armed Activities, Separate Opinion of Judge Kooijmans, para 26.

(77) Wall, Advisory Opinion, Separate Opinion of Judge Kooijmans, para 35.

(78) Armed Activities, Separate Opinion of Judge Kooijmans, para 29.

(79) Armed Activities, Separate Opinion of Judge Simma, para 12, quoting Yoram Dinstein, War, Aggression and Self-Defence (3rd edn, Cambridge: Cambridge University Press, 2002), 216.

(80) Chatham House Principles, 970.

(81) See Trapp, ‘Back to Basics’, 153–5; Gray, International Law and the Use of Force, 237–44.

(82) Identical letters dated 12 July 2006 from the Permanent Representative of Israel to the United Nations addressed to the Secretary-General and the President of the Security Council, A/60/937–S/2006/515.

(83) A/60/937–S/2006/515. Lebanon denied responsibility, insisting that it had been unaware of the incident and did not endorse it. See SCOR, 5489th mtg, S/PV.5489 (14 July 2006), 4.

(84) S/PV.5489, 6.

(85) S/PV.5489, 7, 9, 11–15, and 17; SCOR, 5492nd mtg, S/PV.5492 (20 July 2006), 3; SCOR, 5493rd mtg, S/PV.5493 (21 July 2006), 14; SCOR, 5498th mtg, S/PV.5498 (30 July 2006), 3.

(86) S/PV.5489, 9, 12, and 14–16; S/PV.5493, 17 and 19. The UN Secretary-General also explicitly recognized the right of Israel to take action under Art 51. See S/PV.5492, 3; S/PV.5498, 3.

(87) On the 2007–8 operations in particular, see Tom Ruys, ‘Quo Vadit Jus ad Bellum? A Legal Analysis of Turkey’s Military Operations Against the PKK in Northern Iraq’ (2008) 9 Melbourne Journal of International Law 334; Van Steenberghe, ‘Self-Defence in Response to Attacks by Non-State Actors in the Light of Recent State Practice’, 187–9.

(88) Although see statements by Turkish Prime Minister Erdogan referred to in Van Steenberghe, ‘Self-Defence in Response to Attacks by Non-State Actors in the Light of Recent State Practice’, 188.

(89) This is probably a procedural/evidential rather than substantive requirement, however, which may weaken the case for lawful self-defence—but which does not extinguish it. See Donald W. Greig, ‘Self-Defence and the Security Council: What Does Article 51 Require?’ (1991) 40 International and Comparative Law Quarterly 366.

(90) It is perhaps unclear whether Iraq was unable or unwilling to prevent the attacks, but it did take steps aimed at preventing PKK activities, and received advance warning of Turkish operations in Feb 2008. See Ruys, ‘Quo Vadit Jus ad Bellum?’, 341–2.

(91) See eg ‘EU Presidency Statement on the Terrorist Attacks of the PKK in Turkey over the Weekend’, Press release, 22 Oct 2007, supporting ‘Turkey’s efforts to protect its population and fight terrorism, while…refraining from taking any disproportionate military action’.

(92) Ministerial Statement, 3 Mar 2008, as cited and translated in Ruys, ‘Quo Vadit Jus ad Bellum?’, 356.

(93) Ministerial Statement, 3 Oct 2011: see ‘Dutch Foreign Minister Supports Turkish Cross Border Raids’, available at <http://www.rudaw.net/english/world/4042.html>. See also US Department of State Press Briefings, 18 Aug 2011, at <http://www.state.gov/r/pa/prs/dpb/2011/08/170709.htm#TURKEY>, and 20 Oct 2011, at <http://www.state.gov/r/pa/prs/dpb/2011/10/175929.htm#TURKEY>, outlining US support for Turkey’s right of self-defence against terrorist attacks.

(94) Wall, Advisory Opinion, Separate Opinion of Judge Higgins, para 33. See also Declaration of Judge Buergenthal, para 5.

(95) See n 25; Rein Müllerson, ‘Jus ad Bellum and International Terrorism’ in Fred L. Borch and Paul S. Wilson (eds), International Law Studies, Vol 79: International Law and the War on Terror (Newport, RI: US Naval War College, 2003), 75, 112; Dinstein, War, Aggression and Self-Defence (4th edn, 2005), 193–6, and 219.

(96) Vaughan Lowe, International Law (Oxford: Oxford University Press, 2007), 278.

(97) Simpson, Great Powers and Outlaw States, 334.

(98) See Moir, Reappraising the Resort to Force, 154–5. Schmitt, eg, suggested that one factor in assessing the lawfulness of defensive action against a host state should be ‘the extent to which the state is perceived as generally law-abiding and legitimate’, and that the unpopularity of the Taliban regime ‘made striking them even more palatable’. See Schmitt, ‘Counter-Terrorism and the Use of Force in International Law’ in Borch and Wilson (eds), International Law and the War on Terror, 69–70; Schmitt, ‘The Legality of Operation Iraqi Freedom’, 88.

(99) Van Steenberghe, ‘Self-Defence in Response to Attacks by Non-State Actors in the Light of Recent State Practice’, 195–6.

(100) Van Steenberghe, ‘Self-Defence in Response to Attacks by Non-State Actors in the Light of Recent State Practice’, 199–202; Trapp, ‘Back to Basics’, 146–7 and 154–5.

(101) Maogoto, ‘War on the Enemy’, 438. As Greenwood warned, ‘we do not want to give credence to a theory that as soon as any state has a group of terrorists which have operated from its territory, it exposes itself to armed attack. That very broad brush approach opens up the most horrific possibilities because at some time or other virtually every state however hard it tried otherwise, had ended up with terrorists operating from its territory’. See ‘Panel I Discussion—Jus ad Bellum’ in Borch and Wilson, International Law and the War on Terror, 145.