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The Use of Force in International Law - A Case-Based Approach edited by Ruys, Tom; Corten, Olivier; Hofer, Alexandra (17th May 2018)

Part 3 The Post 9/11-Era (2001–), 52 The Turkish Intervention Against the PKK in Northern Iraq—2007–08

Kimberley N Trapp

From: The Use of Force in International Law: A Case-Based Approach

Edited By: Tom Ruys, Olivier Corten, Alexandra Hofer

From: Oxford Public International Law (http://opil.ouplaw.com). (c) Oxford University Press, 2015. All Rights Reserved. Subscriber: null; date: 10 July 2020

Individuals and non-state actors — Precedent — Armed conflict — Armed attack

(p. 689) 52  The Turkish Intervention Against the PKK in Northern Iraq—2007–08

I.  Facts and Context

Adbullah Öcalan founded the Kurdish Workers’ Party (PKK) in 19781 with a view to establishing an independent and united Kurdistan through armed struggle,2 although its objectives have vacillated between those of its founding and ‘democracy, human rights and cultural and administrative rights within the unitary Turkish entity’.3 Throughout much of its history, the PKK has engaged in a paramilitary campaign against Turkish military forces and the civilian population, peppered by periods of ceasefire.4 In turn, Turkey’s responses have included repressive measures against its Kurdish minority,5 political engagement (principally through the Iraqi Kurdish leadership),6 and military responses against PKK strongholds in both Turkish and Iraqi territory.7

Turkey’s military interventions, coupled with Syria’s withdrawal of support for the PKK8 and the capture of Adbullah Öcalan in 1999, significantly decreased the scale of the security threat posed by the PKK in the early 2000s.9 However, frustrated by Turkey’s limited accommodation of Kurdish demands for increased autonomy, PKK attacks against civilians and Turkish military outposts resumed in 2004.10 From 2004 to the beginning of Turkey’s 2007–08 intervention against the PKK in Northern Iraq, PKK violence claimed over 1,500 lives.11 The Turkish Government repeatedly expressed its concern over the PKK’s paramilitary activities to the United States and Iraq (including the more or less (p. 690) autonomous Iraqi Kurdish authorities),12 in response to which all re-promised to increase their efforts to prevent the PKK from using Northern Iraq as a base of operations.13 Nevertheless, Turkey considered (not without reason14) that too little was being done to address the PKK’s activities and formulated contingency plans for cross-border operations against PKK rebels—with or without Iraqi consent.15

Turkey alleged a series of small scale PKK attacks against Turkish civilian and military targets throughout the spring and summer of 2007,16 but PKK attacks against the Turkish military escalated significantly in October 2007. On Sunday 7 October, thirteen Turkish soldiers were killed in a gun battle with PKK fighters,17 in response to which tens of thousands of Turkish demonstrators took to the streets to protest.18 Despite US and Iraqi calls for restraint, Turkish Prime Minister Erdogan called on Parliament to authorize a Turkish mobilization against the PKK.19 Erdogan’s request was acceded to by the Turkish Parliament with overwhelming support.20

On Sunday 21 October, following the Turkish Parliament’s authorization, PKK fighters attacked a military convoy in Eastern Turkey, killing twelve Turkish soldiers, wounding sixteen, and taking a further eight soldiers captive.21 The Turkish response was immediate, with an aerial bombardment of PKK positions within Iraqi territory.22 Owing to continued diplomatic efforts to resolve the escalating crisis (discussed further in section II below), or at least continued efforts by Turkey to secure US support for sustained airstrikes against PKK bases in return for Turkish restraint in respect of ground operations,23 Turkey held off on larger scale military operations until mid-December 2007.24 In its own (p. 691) bid to stave off Turkish military strikes, the PKK released the eight Turkish soldiers it had been holding captive since its 21 October attack against Turkish troops.25 Turkey, however, repeatedly rejected any offer to negotiate or enter into a ceasefire with the ‘terrorist organisation’.26

Sporadic military operations by Turkey against PKK bases in the fall of 2007 were followed by its largest aerial assault in recent years against PKK camps (in the Qandil Mountains) on 16 December,27 a twenty-four-hour ground incursion on 18 December during which Turkish armed forces clashed with PKK fighters,28 and successive aerial assaults against PKK bases late December.29 Following a suspected PKK attack in south eastern Turkey in the New Year,30 the Turkish military continued its campaign against the PKK into 2008, attacking PKK bases from the air on 15 January 2008,31 and bombarding more than seventy alleged PKK targets in Northern Iraq on 4 February 2008.32

On 21 February, the Turkish air force bombed suspected PKK targets before launching Operation Sun: the largest scale Turkish ground incursion into Iraqi territory in over a decade.33 There were contested reports regarding the number of Turkish troops involved (from 1,000 to 10,000)34 and the scale and intensity of the fighting (with Turkey, the PKK, and Iraq each offering different casualty figures35), but there were certainly casualties on both sides.36 After eight days of ground operations, Turkish troops withdrew from Iraqi (p. 692) territory (less than a day after both President George W Bush and US Defence Secretary Robert Gates urged Turkey to wrap up the operations and made it clear that US support for Turkey was not unlimited).37 In response to continuing PKK attacks against Turkish armed forces, pipelines, and civilian targets,38 Turkey resumed artillery strikes (from Turkish territory) against PKK targets on 6 March 2008,39 and launched further airstrikes against PKK positions in Northern Iraq from the end of March through to July 2008.40 Following an alleged PKK attack against a Turkish border post (killing seventeen Turkish soldiers) in early October 2008, Turkey again launched airstrikes against PKK targets.41

II.  The Positions of the Main Protagonists and the Reaction of Third States and International Organizations

In the weeks following the Turkish parliamentary authorization to use force against the PKK, there were intense diplomatic exchanges between Turkey, Iraq, and the United States, and world leaders weighed in on the crisis with a view to de-escalation. While much sympathy was expressed in regard to Turkey’s PKK-related security challenges, the messages were overwhelmingly in favour of Turkish restraint, not least because of the feared impact of a Turkish intervention on the relative peace in Northern Iraq and regional stability.42 Prime Minister Erdogan made it clear on several occasions that the only way for Iraq to avoid military strikes against the PKK within its territory was ‘the closure of all PKK camps, including their training facilities, and the hand-over of the terrorist leaders to [Turkish authorities]’.43 Iraq’s response wavered between asking for more time;44 offering to ‘actively help’ by restricting the PKK’s movement and financing and putting an end to the external supply of arms and logistical assistance to the PKK;45 and occasionally making strong sounding promises to halt the PKK’s strikes against Turkey from Iraqi (p. 693) territory, none of which were considered sufficient by Turkey.46 For its part, the United States urged the central authorities in Bagdad and the Kurdish authorities in Northern Iraq to take ‘immediate steps’ to halt PKK operations, while at the same time calling on Turkey to exercise restraint and to give diplomacy and cooperation a fair chance.47

Once military operations in Iraqi territory began in earnest, one might have expected Turkey and the main protagonists to shift from political and security speak to the language of the UN Charter. No such shift occurred. In contrast to its operations against the PKK in the 1990s,48 Turkey did not justify its 2007–08 campaign to the Security Council, although it did consistently advance arguments that were ‘Article 51 adjacent’.49 Turkey maintained throughout that it was exclusively targeting the PKK and other ‘terrorist’ targets,50 that it did not consider itself to have any broader right to use force against Iraq’s autonomous Kurdish region or that region’s administration (which it nevertheless accused of harbouring the PKK),51 and consistently denied having ‘any designs’ on Iraqi territory.52

Iraq’s reaction to the Turkish incursions shifted over time—tracking the increasing force used in its territory. In October 2007, Iraq’s focus was principally on the PKK and limiting its activities in Iraqi territory.53 With the heavy bombardment of December 2007, Iraq condemned the Turkish operations as a violation of Iraqi sovereignty, but addressed them principally in terms of their impact on stability in the region.54 In respect of the large scale ground incursion in February 2008, Iraq again condemned Turkey’s use of force as (p. 694) a violation of Iraqi sovereignty,55 this time demanding that it ‘withdraw Turkish troops from Iraqi territory’.56 Iraq also characterized the use of ground forces as an escalation.57 This said, in subsequent statements (while making it clear that the February Turkish operations had not been approved by his government), the Iraqi foreign minister continued to suggest that Iraq’s principal concern was in respect of the potential impact of Turkish operations on stability in the region,58 and that, to the extent Turkey was exercising a right to defend itself against PKK attacks, its operations must be strictly limited to PKK targets.59

In reference to the Turkish aerial attacks against the PKK commencing in October 2007, the United States acknowledged that it had been warned of these and had provided Turkey with intelligence which aided in the selection of relevant targets.60 The United States is also reported to have opened Iraqi airspace to the Turkish military,61 and to have urged Turkey to limit its action to precise targeting of the PKK.62 High level US military officials also stated that ‘the United States backed Turkey’s right to rout the terrorists who have used mountain camps across the border of Iraqi Kurdistan to stage attacks on Turkey’.63 In reference to the February ground offensive, however, the Americans publicly pressured the Turkish authorities to keep the operation short and targeted.64

The international community’s response to the 2007–08 Turkish campaign in Iraq was muted and one which might be characterized as ‘having cake and eating it too’. States spoke in support of the general right to protect civilian populations from terrorism or the need to ensure that territory is not used for terrorist purposes, all the while urging restraint or calling for respect of Iraq’s territorial integrity.65 For instance, the EU both called upon Turkey to ‘respect Iraq’s territorial integrity’ and to ‘limit its military activities to (p. 695) those which are absolutely necessary for … the protection of the Turkish population from terrorism’.66 The EU also relied on the jus ad bellum concept of ‘proportionality’ to urge precision in carrying out any military operations.67 The principal concerns expressed were in respect of the impact of the operations on the precarious peace and security situation in the region.68

III.  Questions of Legality

Turkey’s military intervention in Northern Iraq in 2007–08 was not addressed by states in legal terms, at least not expressly. The intervention nevertheless amounts to a use of force in another state’s territory and thereby engages Article 2(4) of the UN Charter. As the operations were conducted without Iraqi consent69 or Security Council authorization,70 they remain to be legally justified (if at all) on the basis of the inherent right of self-defence and Article 51 of the UN Charter.71

Article 51 of the UN Charter recognizes the inherent right to use defensive force ‘if an armed attack occurs against a Member of the United Nations’ (emphasis added). Turkey is a member of the UN, and was indeed the victim of attacks carried out by the PKK against Turkish military and civilian targets. The first question in respect of the legality of Turkey’s military operations in Iraq, examined in section 1 below, is whether those attacks were of sufficient gravity as to rise to the level of ‘armed attack’ for the purposes of triggering the right of self-defence. The second issue, examined in section 2 below, relates to the nature of the actors carrying out the armed attacks. There has indeed long been a debate regarding the lawfulness of defensive force in response to an armed attack carried out by non-state actors—in particular whether, and to what extent, Articles 2(4) and 51 of the UN Charter can (or should) accommodate non-state actors as independent international (p. 696) actors (addressed further below).72 Finally, as with all uses of force in self-defence, the defensive response must be necessary and proportionate, as examined in section 3 below.

1.  De minimis threshold for ‘armed attack’?

In its Nicaragua decision, the ICJ introduced a de minimis threshold in reference to the ‘armed attack’ trigger for Article 51 of the UN Charter. The Court held that it was necessary to distinguish between ‘the most grave forms of the use of force (those constituting an armed attack) from other less grave forms’.73 Less grave forms of the use of force, as far as the Court is concerned, do not give rise to a right of self-defence on the part of the victim state. The Court further held, at least in respect of irregular armed forces, that an operation would qualify as an ‘armed attack’ if ‘because of its scale and effects, [it] would have been classified as an armed attack rather than as a mere frontier incident had it been carried out by regular armed forces’.74 The Court, however, seems to accept that smaller attacks (presumably those which do not meet its de minimis threshold), taken cumulatively, might nevertheless satisfy the requirement of ‘armed attack’.75

The Court’s de minimis threshold is not without controversy,76 and the Court, operating in declaratory mode, made no effort to derive the requirement from state practice or opinio juris. In any event, the attacks carried out by the PKK against Turkey, in particular those launched on 7 October and 21 October, were deliberate77 cross-border incursions with high casualty figures attached to them. There is no doubt that had such attacks been carried out by Iraq’s armed forces, they would not have been qualified as ‘mere frontier incidents’ and would amount to an armed attack.

2.  The ratione personae element of Article 51

Provided the attacks carried out by non-state actors are of sufficient gravity to amount to ‘armed attacks’ ratione materiae, there is common ground on a victim state’s right to use force in self-defence in response to those attacks if they are attributable to the state from whose territory the non-state actors operate (the host state) and in whose territory defensive force is used. Attribution of non-state actors armed attacks is therefore a sufficient condition in respect of the ratione personae element of Article 51.78 In the case at hand, (p. 697) this would be satisfied if the attacks carried out by the PKK against Turkey were attributable to Iraq. The issue then shifts to the appropriate standard of attribution.79

The standard of attribution relied on by the Court in Nicaragua80 (and again in DRC v Uganda)81 is defined through the Definition of Aggression—in particular Article 3(g) ‘sending by or on behalf of’ standard.82 On the basis of an Article 3(g) standard of attribution, the PKK’s attacks against Turkey are not attributable to Iraq. The Iraqi authorities in Baghdad consistently denounced the PKK’s activities and there is no evidence of the central or Kurdish Iraqi authorities exercising control over the PKK or providing material support of any kind for the PKK which might meet the ‘sending by or on behalf of’ standard as articulated by the ICJ.83

Some scholars, however, have argued that relevant Security Council resolutions84 and post-9/11 state practice85 have lowered the threshold of attribution applicable in the Article 51 context from ‘sending by or on behalf of’ to a standard of complicity.86 As a standard under general international law, complicity might result from a state’s commission (as with responsibility resulting from attribution) or omission (as with a failure to prevent non-state actor conduct),87 and requires aid or assistance in the commission of a wrongful act with actual ‘knowledge of the circumstances of the internationally wrongful act’.88 Complicity is thus in practice difficult to establish, certainly more difficult than a failure to prevent (which would only require constructive knowledge of the attacks).89

(p. 698) Turkey and Iraq entered into a counter-terrorism pact in September 2007,90 requiring both states to take ‘effective measures to prevent the preparation and commission of terrorist acts aimed at the security, territorial integrity and inviolability of borders and safety of citizens of the other party’.91 The PKK’s attacks against Turkish military targets worsened significantly in the month following signature of the pact.92 There is little doubt that the attacks amounted to a failure by Iraq to prevent the activities of the PKK against Turkey, perhaps even a culpable failure.93 However, a mere failure to prevent is not sufficient for complicity. There is no evidence that Iraqi authorities, central or regional, had actual knowledge of the armed attacks the PKK launched against Turkey, or that they failed to act with a view to assisting the PKK in the commission of such attacks. On this basis alone, Iraq’s conduct does not rise to complicity in the sense of Article 16 of the Articles on Responsibility of States for Internationally Wrongful Acts. As a result, even on an alternative (and lower) standard of attribution, the PKK’s attacks are not attributable to Iraq.

The PKK’s attacks against Turkey are not attributable to Iraq on either the Article 3(g) of the Definition of Aggression standard or on the lower complicity standard. In order to determine whether Turkey’s intervention against the PKK in Northern Iraq in 2007–08 was nevertheless lawful, the question remains whether attribution is a necessary feature of the ratione personae element of ‘armed attack’ in respect of non-state actors. The answer depends in large part on whether the Article 51 right to use force in self-defence is conceptualized as a responsive right (like a countermeasure), such that it is triggered only in response to a prior breach of Article 2(4) of the UN Charter (in the particular form of an armed attack) by the state in whose territory defensive force is used.94 As Article 2(4) only expressly contemplates inter-state force, if Article 51 is a responsive right, then it too is limited to an inter-state context. There is, however, nothing in the legal history pre-dating the UN Charter, or the travaux preparatoires of the UN Charter, to support a responsive reading of Article 51 of the UN Charter.95

An alternative reading of Article 51 (one that has not been addressed in most of the academic commentary), is that it is an independent right, operating on its own terms and in some respects independently from Article 2(4), on the basis of its being characterized as ‘inherent’.96 As an independent right, Article 51 would preclude the wrongfulness of a use of defensive force in the host state’s territory, otherwise in breach of Article 2(4), irrespective of the prior wrongful act of the host state. As a result, on this author’s view, there (p. 699) is no need for the armed attack by the PKK to be attributable to Iraq in order that Turkey’s use of defensive force be lawful. As a non-responsive circumstance precluding wrongfulness, Article 51 operates on its own terms—triggered by an ‘armed attack’. It is widely acknowledged that there is nothing express in the language of Article 51 which restricts ‘armed attacks’ to attacks carried out by or on behalf of states.97 Nor does the negotiating history of the UN Charter suggest that such a restriction should be read into Article 51.98 On this reading of Article 51, the legal analysis is therefore focused entirely on whether the relevant facts trigger the right to use force in self-defence (in the form of an ‘armed attack’) and whether the exercise of that right once triggered meets the customary international law requirements of necessity and proportionality,99 each as discussed below.

3.  Necessity and proportionality

However the right to use force in self-defence is conceived—as a responsive right requiring the attribution of non-state actor armed attacks to the host state, or as an independent right triggered on its own terms (in particular, an ‘armed attack’, whether committed by a state or non-state actors)—the defensive force must be both necessary and proportionate.100 Necessity and proportionality operate to limit the right to use force in self-defence in two ways. The first bears on the question of whether a use of force is necessary at all—particularly where there are alternative (peaceful and diplomatic) mechanisms for protecting the victim state.101 The principle of proportionality further constrains a use of force in self-defence—requiring that the defensive force be specifically tailored to halt or repel the armed attack to which it is responding.

As noted above, Turkey and Iraq entered into a counter-terrorism pact in September 2007, by way of which the two states agreed ‘to prevent terrorist groups from using their respective territories as bases for presence, recruitment, training, planning, inciting or launching of terrorist acts against the other party’.102 In signing the pact, Iraq certainly wanted to appear willing to prevent the PKK from using its territory as a base of operations against Turkey. Nonetheless, Iraq’s refusal to extradite PKK fighters to Turkey on the basis of their arrest being ‘impossible’,103 and continued reference to a lack of resources and the difficult terrain from which the PKK operated in defence of prevention failures,104 make it clear that Iraq was in fact unable to do so. This author has argued elsewhere that where a host state is unwilling or unable to prevent its territory from being used as a base of armed attacks non-state actors, a use of defensive force by the victim state satisfies the legal requirement of necessity.105 Erdogan certainly claimed a right to ‘destroy [terrorist] (p. 700) shelters ourselves’ in the event they were not destroyed by the territorial sovereign (accepting that Iraq’s willingness and ability to act against the PKK would render Turkish force unnecessary).106

As to whether Turkey’s incursions against the PKK into Northern Iraq in 2007–08 were specifically tailored to halt or repel the armed attacks to which it was responding, the facts are somewhat contested. By Turkey’s own account, its operations were limited to the mountainous border region from which the PKK operated.107 Limiting defensive operations to relevant territory is an element in favour of a finding of proportionality.108 Turkey also claimed its operations avoided civilian casualties, although this particular claim was rather heavily contested.109 The effects of defensive operations on the civilian population (of the state in whose territory defensive force is used) is an element of the proportionality calculus,110 but without clearer facts, more than that cannot be said. On the whole, the proportionality of Turkey’s operations depends on whether its means and methods were tailored to a defensive purpose. In addition to repelling particular attacks, Turkey’s operation seems to have been aimed at weakening the PKK generally.111 Such aims may be consistent with a defensive purpose in circumstances where several previous armed attacks have been carried out, and the victim state anticipates further imminent attacks.112

IV.  Conclusion: Precedential Value

Turkey’s use of force in Iraqi territory spanned over a full year between October 2007 and October 2008, relying on both air and ground forces.113 The Turkish incursions against the PKK in Northern Iraq undoubtedly were a breach of Article 2(4) of the UN Charter in need of a circumstance precluding wrongfulness. Yet the discourse surrounding the Turkish interventions was framed in terms of the stability of the region114 and the security challenges of terrorism,115 not the Charter framework or the applicability of Article 51. Part of the reason for this is evidently the debate regarding the nature of the right to use force in self-defence against non-state actors, and the necessary conditions for the invocation of Article 51. While state practice increasingly supports a state’s right to respond to cross-border attacks by non-state actors116 as Turkey did (provided the response is defensive, necessary, and proportionate), the ICJ did not take the opportunity to address the practice in its 2005 DRC v Uganda decision,117 and attribution as sine qua non of a right to use force in self-defence in response to NSA attacks remains a feature of the legal debate.

(p. 701) This author is of the view that we have moved past attribution and a state-centric approach to the UN Charter, such that Turkey at least had the right to use force in self-defence in response to armed attacks by the PKK. Indeed, state reactions to the Turkish intervention suggest as much. States spoke in support of Turkey’s right to defend its civilian population against terrorist attacks and did so in the context of addressing its operations against the PKK.118 Implicit in such an approach is the recognition that non-state actors can mount attacks which may warrant a defensive response. Furthermore, several states addressed the Turkish intervention in terms of its jus ad bellum proportionality.119 An invocation of proportionality relies on Article 51 of the UN Charter as the appropriate framework within which to evaluate Turkey’s use of force. As the PKK’s conduct is very evidently not attributable to Iraq, such invocations implicitly accept the right to use force in self-defence as an independent right—triggered by an armed attack, whatever its source. Of particular interest on this last point, both Iraq and the United States seemed to accept the right to target (very precisely of course) the PKK’s camps.120 Taken as a whole, the international community’s response to the Turkish intervention in Northern Iraq in 2007–08 would seem to support the view that the Article 51 right of self-defence covers targeted operations in response to armed attacks by non-state actors. Whether exercising such a right, in the context of separatist aspirations or demands for cultural autonomy, is a wise and winning strategy, however, remains to be seen.


1  See Aliza Marcus, Blood and Belief: The PKK and the Kurdish Fight for Independence (NYU Press 2007) 18–21; International Crisis Group (ICG), ‘Turkey: Ending the PKK Insurgency’ Europe Report No 213 (20 September 2011) 1; ICG, ‘Turkey and Iraqi Kurds: Conflict or Cooperation?’, Middle East Report No 81 (13 November 2008).

2  ICG, ‘Turkey: The PKK and a Kurdish Settlement’ Europe Report No 219 (11 September 2012), 7.

3  William Hale, Turkey, the US and Iraq (SOAS Middle East Issues 2007, kindle edition), 811–26. See also ‘Turkey: Ending the PKK Insurgency’ (n 1) 2.

4  See, generally, Marcus (n 1); ‘Turkey: The PKK and a Kurdish Settlement’ (n 2) 5; Hale (n 3) 811–26.

5  See ‘Turkey: Ending the PKK Insurgency’ (n 1) 4–5.

6  See Hale (n 3) 725–66.

7  Between 1991 and 1999, the PKK took advantage of the confusion in Northern Iraq following coalition operations there and increased its attacks against both Turkish military posts and civilians. ICG, ‘Turkey: Ending the PKK Insurgency’ (n 1) 4. In response, Turkey claimed a right to resort to measures necessary to protect its security, including the use of force against PKK elements operating from Iraqi territory, without Iraqi consent. (January 1994) 40 Keesing’s Record of World Events (Keesing’s) 39834; (March 1995) 41 Keesing’s 40473; (May 1997) 43 Keesing’s 41651; (October 1997) 43 Keesing’s 41877.

8  Syria withdrew its support for the PKK following Turkish threats of military retaliation. See Henri J Barkey, ‘Turkey and the PKK: A Pyrrhic Victory?’ in Robert J Art and Louise Richardson (eds), Democracy and Counterterrorism: Lessons from the Past (US Institute of Peace Press 2007) 343, 362–63.

9  ‘Turkey: Ending the PKK Insurgency’ (n 1) 4–5. Between 2000 and 2004, the PKK also implemented a unilateral ceasefire, no doubt partly in response to their weakened position.

10  See ‘Turkey: Ending the PKK Insurgency’ (n 1) 4.

11  International Institute for Strategic Studies, ‘Turkey: New Uncertainties’ (2007) 107 Strategic Survey 178, 180.

12  See, eg, OIC, ‘Secretary General receives Turkish minister of Foreign Affairs’ (22 October 2007) <http://www.oic-oci.org/topic/?t_id=572&ref=282&lan=en>; ‘Turkey draws up plan for possible attack on Kurds in Iraq’ New York Times (New York, 6 July 2007) <http://www.nytimes.com/2007/07/06/world/africa/06iht-turkey.4.6537622.html>; Ellen Knickmeyer, ‘Turkey to Warn Iraq on Rebel Sanctuaries’ The Washington Post (Washington DC, 6 August 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/08/05/AR2007080501262.html>.

13  See (July 2006) 52 Keesing’s 47377–78; (July 2006) 52 Keesing’s 47377–78; (March 2007) 53 Keesing’s 47831; (October 2007) 53 Keesing’s 48219; (September 2007) 53 Keesing’s 48151.

14  (October 2007) 53 Keesing’s 48219. See also 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, 337.

15  (May 2007) 53 Keesing’s 47949; (July 2007) 53 Keesing’s 48050; ‘Turkey Draws up Plan for Possible Attack on Kurds in Iraq’ (n 12).

16  (May 2007) 53 Keesing’s 47949; (August 2007) 53 Keesing’s 48094.

17  (October 2007) 53 Keesing’s 48219; ‘Kurdish Rebels Kill 13 Soldiers on Turkish Border with Iraq’, New York Times (New York, 8 October 2007) <http://www.nytimes.com/2007/10/08/world/europe/08turkey.html>.

18  (October 2007) 53 Keesing’s 48219.

19  Molly Moore and Robin Wright, ‘U.S. Urges Turkish Restraint on Kurds’ The Washington Post (Washington DC, 14 October 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/10/13/AR2007101301427.html>.

20  By a vote of 507 to 19, the Turkish Parliament authorized Prime Minister Erdogan to order strikes against the PKK, in Iraqi territory, for a period of one year. Molly Moore, ‘Turkey Authorizes Iraq Incursion’ The Washington Post (Washington DC, 18 October 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/10/17/AR2007101700967.html>.

21  (October 2007) 53 Keesing’s 48219–20; Amit R Paley, ‘Kurds from Iraq Kill 17 Soldiers in Turkey’ The Washington Post (Washington DC, 22 October 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/10/21/AR2007102100172.html>. This second PKK attack was apparently in response to an earlier penetration of Turkish helicopter gunships into Iraqi territory and the shelling of PKK positions. ‘Turkey Admits Shelling and Flyovers on Kurdish Positions in Iraq’ New York Times (New York, 24 October 2007) <http://www.nytimes.com/2007/10/24/world/africa/24iht-turkey.2.8033904.html>.

22  (October 2007) 53 Keesing’s 48220.

23  (November 2007) 53 Keesing’s 48265.

24  (December 2007) 53 Keesing’s 48316; (December 2007) 53 Keesing’s 48326. Turkish forces had carried out a number of more limited military operations against PKK fighters throughout the fall and into early December 2007. See ‘Turkey “Hits PKK Targets in Iraq”’ Aljazeera.net (24 October 2007) <http://english.aljazeera.net/NR/exeres/14FA7823-911C-4456-B8DB-6CD27C4DE07F.htm>; (November 2007) 53 Keesing’s 48265; ‘Turkish Cabinet Gives Green Light to Army, which Attacks Kurds’ New York Times (New York, 1 December 2007) <http//www.nytimes.com/2007/12/01/world/africa/01iht-turkey.1.8554326.html?mtrref=undefined>; ‘Turkey “Right to Intervene in Iraq” ’ Aljazeera.net (3 December 2007) <http://www.aljazeera.com/news/europe/2007/12/2008525143433545716.html>.

25  (November 2007) 53 Keesing’s 48265; ‘Kurdish Rebels Free 8 Turkish Soldiers’ The Washington Post (Washington DC, 4 November 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/11/04/AR2007110400267_pf.html>.

26  ibid.

27  (December 2007) 53 Keesing’s 48316; (December 2007) 53 Keesing’s 48326; Damien Cave, ‘Iraq Leaders Denounce Bombings by Turkey’ New York Times (New York, 18 December 2017) <http://www.nytimes.com/2007/12/18/world/middleeast/18iraq.html?mtrref=undefined>; ‘Iraq Condemns Turkish Air Raids’ Al-Jazeera (17 December 2017) <http://www.aljazeera.com/news/europe/2007/12/2008525134932579331.html>. Several news outlets reported that the Turkish air raids affected civilian villages in the region. See ibid; Ann Scott Tyson and Robin Wright, ‘U.S. Helps Turkey Hit Rebel Kurds in Iraq’ The Washington Post (Washington DC, 18 December 2017) <http://www.washingtonpost.com/wp-dyn/content/article/2007/12/17/AR2007121702150.html>.

28  See (December 2007) 53 Keesing’s 48316; Sudarsan Raghavan and Ellen Knickmeyer, ‘Turkey Sends Troops into Iraq to Battle Kurdish Rebels’ The Washington Post (19 December 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/12/18/AR2007121800230.html>.

29  (December 2007) 53 Keesing’s 48316; Joshua Partlow and Dlovan Brwari, ‘Turkish Planes Bomb Northern Iraq for Second Consecutive Day’ The Washington Post (24 December 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/12/23/AR2007122301512.html>.

30  The attack against a military vehicle killed 4 and injured 52. ‘Bombing kills at least 4 in Turkey’ New York Times (New York, 3 January 2007) <http://www.nytimes.com/2008/01/03/world/europe/03iht-turkey.4.9011733.html?mtrref=undefined>.

31  (January 2008) 54 Keesing’s 48374.

32  Amit R Paley and Dlovan Brwari, ‘Turkey Bombs Villages in N. Iraq’ The Washington Post (Washington DC, 5 February 2008) <http://www.washingtonpost.com/wp-dyn/content/article/2008/02/04/AR2008020400606.html>.

33  (February 2008) 54 Keesing’s 48427; Paul de Bendern, ‘Turkey Launches Major Land Offensive into N. Iraq’ Reuters (United States, 22 February 2008) <http://www.reuters.com/article/us-turkey-iraq-idUSANK00037420080222>; Sabrina Tavernise and Sebnem Arsu, ‘Turkey Says it Has Sent Ground Troops into Iraq’ New York Times (New York, 22 February 2008) <http://www.nytimes.com/2008/02/22/world/middleeast/22iraq.html>.

34  ‘Turkey Steps Up Iraq Offensive’ Al-Jazeera (24 February 2008) <www.aljazeera.com/news/europe/2008/02/2008525144527240486.html>.

35  ‘Turkey Urges PKK to End Struggle’ BBC News (1 March 2008) <http://news.bbc.co.uk/2/hi/europe/7272184.stm>.

36  ‘Turkey Ignores Iraq Pull-Out Plea’ Al-Jazeera (25 February 2008) <http://www.aljazeera.com/news/middleeast/2008/02/200852512303980176.html>; Sudarsan Raghavan, ‘Iraq Sounds Alarm on Clashes in North’ The Washington Post (Washington DC, 26 February 2008) <http://www.washingtonpost.com/wp-dyn/content/article/2008/02/25/AR2008022502902.html>.

37  (February 2008) 54 Keesing’s 48427; (February 2008) 54 Keesing’s 48441; ‘Turkish Troops Pull Out of Iraq’ BBC (29 February 2008) <http://news.bbc.co.uk/2/hi/europe/7270566.stm>.

38  See (May 2008) 54 Keesing’s 48595.

39  Joshua Partlow, ‘Turkey Resumes Strikes in Iraq’s North’ The Washington Post (Washington DC, 6 March 2008) <http://www.washingtonpost.com/wp-dyn/content/article/2008/03/05/AR2008030503066.html>.

40  54 (March 2008) Keesing’s 48480; ‘Turkey Hits Rebel Targets in Iraq’ BBC (29 March 2008) <http://news.bbc.co.uk/2/hi/europe/7320508.stm>; 54 (April 2008) Keesing’s 488545; ‘Turkey Launches Raids on N Iraq’ BBC (26 April 2008) <http://news.bbc.co.uk/2/hi/europe/7368541.stm>. The operations in Iraq coincided with ground operations by the Turkish armed forces against PKK fighters in the Turkish provinces of Bingöl, Şirnak, and Hakâri. 54 (April 2008) Keesing’s 48545; 54 (May 2008) Keesing’s 48595; ‘Turkey “Kills 150 Kurdish Rebels” ’ BBC (3 May 2008) <http://news.bbc.co.uk/2/hi/middle_east/7382150.stm>; (July 2008) 54 Keesing’s 48701; ‘Turkish Jets Target PKK in Iraq’ BBC (24 July 2008) <http://news.bbc.co.uk/2/hi/europe/7523020.stm>.

41  Sabrina Tavernise, ‘Turkey Re-Authorizes Strikes in Iraq’ New York Times (New York, 9 October 2008) <http://www.nytimes.com/2008/10/09/world/europe/09iht-09turkey.16801289.html?mtrref=undefined&mtrref=www.nytimes.com>.

42  See, eg, Presidency of the EU, ‘EU Presidency Statement on the Terrorist Attacks of the PKK in Turkey over the Weekend’ (22 October 2007) quoted in Ruys (n 14) 340.

43  ‘Prime Minister of Turkey Calls on Iraq to Shut Camps of Kurdish PKK rebels’ New York Times (New York, 19 October 2007) <http://www.nytimes.com/2007/10/19/world/africa/19iht-turkey.4.7965280.html>.

44  Both the Iraqi and Iraqi Kurdish authorities maintained that it was unrealistic to expect them to close the camps, as the terrain from which the PKK operated was inaccessible and difficult and they lacked the military resources to do so. See Andrew E Kramer and Sebnem Arsu, ‘Iraq Wants Turkey to Accept Baghdad’s Offer to Deal with Kurd Rebels’ New York Times (New York, 25 October 2007) <http://www.nytimes.com/2007/10/25/world/europe/25iht-turkey.5.8059564.html?mtrref=undefined>; Sabrina Tavernise, ‘In the Rugged North of Iraq, Kurdish Rebels Flout Turkey’ New York Times (New York, 29 October 2007) <http://www.nytimes.com/2007/10/29/world/middleeast/29kurds.html?mtrref=undefined>.

45  James Glanz and Andrew Krameroct, ‘US Envoy Presses Iraq to Act Against Guerrillas’ New York Times (New York, 26 October 2007) <http://www.nytimes.com/2007/10/26/world/europe/26turkey.html?mtrref=undefined>.

46  See Sudarsan Raghavan, ‘Maliki, Under Turkish Pressure, Vows to Curb Kurdish Rebels’ The Washington Post (Washington DC, 24 October 2017) <http://www.washingtonpost.com/wp-dyn/content/article/2007/10/23/AR2007102300377.html?sid=ST2007102301577>; ‘Iraq Wants Turkey to Accept Baghdad’s Offer to Deal with Kurd Rebels’ (n 45); ‘Under Pressure, Maliki Vows to Help End Kurdish Attacks on Turkey’ New York Times (New York, 3 November 2007) <http://www.nytimes.com/2007/11/03/world/africa/03iht-turkey.1.8174084.html>.

47  Robin Wright and Michael Abramowitz, ‘U.S. Warns Iraq to Halt Rebel Raids on Turkey’ The Washington Post (Washington DC, 23 October 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/10/22/AR2007102200746.html/>.

48  See Christine Gray and Simon Olleson, ‘The Limits of the Law on the Use of Force: Turkey, Iraq and the Kurds’ (2001) 12 Finnish Yearbook of International Law 355.

49  Erdogan characterized the situation as one of ‘self-defence’ to his own party (Sebnem Arsu, ‘Iraq Moves to Dissuade Turkey from Raids’ New York Times (New York, 17 October 2007) <http://www.nytimes.com/2007/10/17/world/europe/17turkey.html>), but did not otherwise use the language of Article 51 UNC in public statements.

50  ‘US Denies Backing Turkey PKK raid’ BBC (17 December 2007) <http://news.bbc.co.uk/2/hi/europe/7147375.stm>. Turkey particularly emphasized the limited nature of its operations in reference to the February 2008 ground incursion, which it characterized as ‘an operation of limited duration to specifically target P.K.K. terrorists in that region’ (Alissa J Rubin and Sabrina Tavernise, ‘Turkish Troops Enter Iraq in Pursuit of Kurdish Militants’ New York Times (New York, 23 February 2008) <http://www.nytimes.com/2008/02/23/world/middleeast/23turkey.html>), although Erdogan also said that the ‘objective [of the operation] is the elimination of PKK terrorism’. ‘Iraq Incursion Finished, Turkey Says’ CNN (29 February 2008) <http://edition.cnn.com/2008/WORLD/meast/02/29/iraq.main/index.html>.

51  ‘Turkey Demands Extradition of Kurdish Rebels from Iraq’ New York Times (New York, 26 October 2007) <http://www.nytimes.com/2007/10/26/world/europe/26iht-turkey.4.8070613.html>; Anne Gearan, ‘Iraq Pledges to Fight Kurdish Rebels’ The Washington Post (Washington DC, 4 November 2017) <http://www.washingtonpost.com/wp-dyn/content/article/2007/11/04/AR2007110400467.html>; Joshua Partlow and Molly Moore, ‘Turkish Premier Faults Allies on Kurdish Issue’ The Washington Post (Washington DC, 26 October 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/10/25/AR2007102501539.html>.

52  Amit R Paley, ‘Kurds from Iraq Kill 17 Soldiers in Turkey’ The Washington Post (Washington DC, 22 October 2007 <http://www.washingtonpost.com/wp-dyn/content/article/2007/10/21/AR2007102100172.html>. In a note to the Human Rights Council regarding the operations (in response to a joint statement submitted by NGOs in respect thereof), Turkey stated that it ‘targeted solely the PKK … terrorist presence’ and that it ‘remains a staunch advocate of the territorial integrity and sovereignty of Iraq’. ‘Note Verbale Dated 26 March 2008 from the Permanent Mission of Turkey to the United Nations Office at Geneva Addressed to the Secretariat of the Human Rights Council’ (28 March 2008) UN Doc A/HRC/7/G/15.

53  ‘Dozens Die in Turkey Border Clash’ BBC (21 October 2007) <http://news.bbc.co.uk/2/hi/europe/7055004.stm>.

54  (December 2007) 53 Keesing’s 48316.

55  (February 2008) 54 Keesing’s 48427; ‘Toll Rises in Turkey-PKK Conflict’ Aljazeera.net (25 February 2008) <http://english.aljazeera.net/NR/exeres/3E14DD15-F2D1-4C65-8148-5200DFB3E975.htm>.

56  ‘Turkish Troops Enter Iraq in Pursuit of Kurdish Militants’ (n 50). As the fighting in Northern Iraq continued into a sixth day, the Iraq Government increased the volume on its demands that Turkish troops withdraw from its territory. Michael Kamber, ‘Iraq Cabinet Demands Turks Leave Kurdish Area in North’ New York Times (New York, 27 February 2008) <http://www.nytimes.com/2008/02/27/world/middleeast/27iraq.html>.

57  ibid. See further Joshua Partlow and Amit R Paley, ‘Turkey Sends Soldiers into N. Iraq’ The Washington Post (Washington DC, 23 February 2008) <http://www.washingtonpost.com/wp-dyn/content/article/2008/02/22/AR2008022202919.html>.

58  ‘Iraq Warns Turkey Over Incursion’ BBC (23 February 2008) <http://news.bbc.co.uk/2/hi/europe/7260478.stm>.

59  ibid. Paul de Bendern, ‘Turkey Launches Major Land Offensive into N. Iraq’ Reuters (United States, 22 February 2008) <http://www.abc.net.au/news/2008-02-23/turkey-launches-land-offensive-into-northern-iraq/1051450?site=news>.

60  See (December 2007) 53 Keesing’s 48316; Ann Scott Tyson and Robin Wright, ‘U.S. Helps Turkey Hit Rebel Kurds in Iraq’ The Washington Post (Washington DC, 18 December 2017) <http://www.washingtonpost.com/wp-dyn/content/article/2007/12/17/AR2007121702150.html>.

61  (December 2007) 53 Keesing’s 48316; ‘Turkey Says It Has Sent Ground Troops into Iraq’ (n 33).

62  ibid. See also ‘Iraq condemns Turkish air raids’ (n 27).

63  ‘Turkish Troops Enter Iraq in Pursuit of Kurdish Militants’ (n 50).

64  Helene Cooper and David S Cloudoct, ‘Bush Administration Urges Iraqi Kurds to Help End Raids into Turkey’ New York Times (New York, 23 October 2007) <www.nytimes.com/2007/10/23/washington/23policy.html>; ‘Turkey Must End Iraq Raid — Bush’ BBC (28 February 2008) <http://news.bbc.co.uk/2/hi/europe/7268345.stm>; Richard A Oppel Jr and Mark Mazzetti, ‘Gates Urges Limits on Turkish Raids’ New York Times (New York, 28 February 2008) <http://www.nytimes.com/2008/02/28/world/middleeast/28iraq.html>.

65  See, eg, EU, ‘EU Presidency Statement on the Military Actions Undertaken by Turkey on Iraqi Territory’ (25 February 2008), <http://www.eu2008.si/en/News_and_Documents/CFSP_Statements/February/0225MZZturkey.html>; OIC, ‘OIC Secretary General calls for continuation of dialogue between Turkey and Iraq’ (27 February 2008) <http://www.oic-oci.org/topic/?t_id=861&ref=406&lan=en>; Russia, ‘Russian MFA Spokesman Mikhail Kamynin Answers a Media Question Regarding Situation on Turkish-Iraqi Border’ (22 February 2008) <http://russiaun.ru/en/news/200802221998>; Japan, ‘Statement by Press Secretary/Director-General for Press and Public Relations, Ministry of Foreign Affairs, on the Recent Situation on Attacks by the Kurdistan Workers’ Party(PKK)’ (22 October 2007) <http://www.mofa.go.jp/announce/announce/2007/10/1175847_836.html>. See further Ruys (n 14) 343–44; Christian Tams and James G Devaney, ‘Applying Necessity and Proportionality to Anti-Terrorist Self-Defence’ (2012) 45(1) Israel Law Review 91, 94.

66  ‘EU Presidency Statement on the Military Action Undertaken by Turkey in Iraqi Territory’ (n 65).

67  ibid.

68  See n 65; (June 2007) 53 Keesing’s 48009. See further Michael Evans, ‘Analysis: Invasion Would be a Disaster’ Times Online (United Kingdom, 21 October 2007) <http://www.timesonline.co.uk/tol/news/world/iraq/article2707317.ece>.

69  Until 1990, there was a cooperative arrangement between Ankara and Bagdad, by way of which the two states mutually consented to the pursuit of Kurdish elements into the other state’s territory when necessary for security operations. This arrangement ended with Turkey’s support for the coalition campaign against Iraq following Iraq’s invasion and occupation of Kuwait. See Hale (n 3); ‘Turkey and Iraqi Kurds: Conflict or Cooperation?’ (n 1) 1. There were rumours that Turkey and Iraq were considering including a right of hot pursuit by the Turkish military against PKK fighters in the counter-terrorism pact they negotiated in September 2007 (The Associated Press, ‘Turkey, Iraq Agree on Kurdish Rebels’ The Washington Post (Washington DC, 26 September 2007) <http://www.washingtonpost.com/wp-dyn/content/article/2007/09/26/AR2007092600413.html>), but under apparent pressure from the Iraqi Kurdish leadership, this feature of the pact was dropped (‘Iraq Rejects Turkish Demands in Anti-Terror Deal’ New York Times (New York, 28 September 2007) <http://www.nytimes.com/2007/09/28/world/africa/28iht-28iraq.7671792.html>).

70  Turkey’s 2007–08 operations in Northern Iraq were not the subject of any report by Turkey to the UNSC, nor any letter of complaint by Iraq or other interested states to the UNSC. As a result, the interventions were not the subject of any debate at all within the Council.

71  For further discussion of the legality of Turkish operations in Northern Iraq in 2007–08, see Isabelle Moulier, ‘L’emploi de la force par la Turquie contre le parti des travailleurs du Kurdistan (PKK) dans le nord de l’Irak’ (2008) 54 Annuaire français de droit international 143; Ruys (n 14); Raphael 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; Theresa Reinold, ‘State Weakness, Irregular Warfare, and the Right to Self-defense Post-9/11’ (2011) 105 American Journal of International Law 244, 268ff; Tams and Devaney (n 65).

72  See Kimberley Trapp, ‘Actor-pluralism, the “Turn to Responsibility” and the Jus Ad Bellum: “Unwilling or Unable” in Context’ (2015) 2 Journal on the Use of Force and International Law 199.

73  Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America) (Merits, Judgment) [1986] ICJ Reports 14, [191].

74  ibid [195].

75  Oil Platforms (Islamic Republic of Iran v United States of America) (Judgment) [2003] ICJ Reports 161, [72]; Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v Uganda) (Judgment) [2007] ICJ Reports 43, [146].

76  Tarcisio Gazzini, The Changing Rules on the Use of Force in International Law (Manchester University Press 2006) 138–39; Elizabeth Wilmshurst, ‘The Chatham House Principles of International Law on the Use of Force in Self‐Defence’ (2006) 55 International and Comparative Law Quarterly 963; William Taft, ‘Self-Defense and the Oil Platforms Decision’ (2004) 29 Yale Journal of International Law 295, 302. But see Olivier Corten, The Law Against War: The Prohibition on the Use of Force in Contemporary International Law (Hart 2010) 403.

77  In Nicaragua (n 73) [231] and Oil Platforms (n 75) [64], the Court also seems to suggest that armed attacks need to at least be intentionally launched against the ultimate victim, if not motivated by an animus aggresionis. See further Christine Gray, International Law and the Use of Force (OUP 2008) 145.

78  The International Court of Justice (ICJ) is often understood to have held that attribution to the host state is also a necessary condition, absent which there is no right to use defensive force in response to armed attacks by NSAs. See, eg, Scott M Malzahn, ‘State Sponsorship and Support of International Terrorism: Customary Norms of State Responsibility’ (2002) 26 Hastings International and Comparative Law Review 83; Olivier Corten, ‘Opération “liberté immutable”: Une éxtension abusive du concept de légitime defence’ (2002) 106 Revue générale de droit international public 51, 55. For an alternative reading of the Court’s decisions, accepting attribution as a sufficient condition, but arguing that the Court did not hold attribution to be a necessary condition, see Kimberley Trapp, ‘Back to Basics’ (2007) 56 International and Comparative Law Quarterly 141.

79  See Christian Tams, ‘The Use of Force against Terrorists’ (2009) 20 European Journal of International Law 359; Kimberley Trapp, ‘The Use of Force against Terrorists: A Reply to Christian J. Tams’ (2009) 20 European Journal of International Law 1049.

80  See Nicaragua (n 73) [195].

81  Armed Activities on the Territory of the Congo (Democratic Republic of the Congo v Uganda) (Judgment) [2007] ICJ Reports 43, [146].

82  UN Definition of Aggression, UNGA Resolution 3314 (XXIX) (14 December 1974) UN Doc A/RES/3314 (XXIX), Annex, Article 3(g): ‘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 [the acts of aggression listed in the resolution], or its substantial involvement therein.’ While the Definition of Aggression was adopted for the purposes of directing the Security Council in its exercise of Chapter VII powers, the ICJ relies on the definition in defining the scope of ‘armed attack’ under Article 51, without ever expressly equating ‘armed attack’ and ‘aggression’. See Kimberley Trapp, State Responsibility for Terrorism (OUP 2011) § 2.1.1.

83  The ICJ’s interpretation of Article 3(g) in both Nicaragua (n 73) and DRC v Uganda (n 75) focuses on the ‘sending by or on behalf of’ language, and does not speak to ‘substantial involvement therein’—which language may well have covered lower levels of involvement in the activities of NSAs. For contemporaneous critiques of this particular feature of the Court’s decision, see Nicaragua (n 73) 543 (Dissenting Opinion of Judge Jennings) and 131–33 (Dissenting Opinion of Judge Schwebel); John N Moore, ‘The Secret War in Central America and the Future of World Order’ (1986) 80 American Journal of International Law 43–127. In respect of the facts of Nicaragua, the United States provided strong material support to the contras, including military supplies, communications equipment, intelligence on Sandinista troop movements, and training. See Nicaragua (n 73) [100]–[115]. This support was not sufficient for the purposes of meeting the Article 3(g) standard of attribution articulated by the Court.

84  In particular, see UNSC Resolution 1368 (10 September 2001) UN Doc S/RES/1367; UNSC Resolution 1373 (28 September 2001) UN Doc S/RES/1373.

85  For a review of the practice, see Trapp (n 78) and Ruys (n 14).

86  See, eg, Tams (n 79).

87  See Helmut Philipp Aust, Complicity and the Law of State Responsibility (CUP 2011) []; Lanovoy, ‘Complicity in an Internationally Wrongful Act’, Shares Research Paper 38 <http://www.sharesproject.nl/publication/complicity-in-an-internationlly-wrongful-act/> 11.

88  Article 16(a) of the Articles on Responsibility of States for Internationally Wrongful Acts, with Commentaries, Report of the International Law Commission on the work of its fifty-third session, (2001) UN Doc A/56/10, 31.

89  In reference to the obligation to prevent in the Genocide Convention, the Court held that, for a state to incur responsibility, ‘it is enough that the State was aware, or should normally have been aware, of the serious danger that acts of genocide would be committed’ (emphasis added). Case concerning the Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro) (Judgment) [2007] ICJ Reports 43, [432].

90  See n 69.

91  ‘Agreement between the Republic of Iraq and The Republic of Turkey on Combating Terrorism’ (28 September 2007) <http://ekurd.net/mismas/articles/misc2007/10/government1223.htm> Article I.

92  See nn 17–21 and accompanying text.

93  The obligation to prevent is an obligation of conduct subject to a due diligence standard, and available means is the limit of responsibility for breach thereof (see Trapp (n 82) [3.1]). The Iraqi Kurdish authorities repeatedly noted the very difficult terrain from which the PKK operated and, along with the central Iraqi authorities, suggested a lack of available resources accounted for the failure to prevent. See n 44 and accompanying text. Nevertheless, Iraqi Kurdish authorities had managed to assist Turkey in its fight against the PKK in the 1990s, and had refused to extradite PKK fighters to Turkey (see Ruys (n 14) 358), suggesting the failure was a mixture of inability and unwillingness.

94  See Roberto Ago, ‘Eighth report on State responsibility —the internationally wrongful act of the State, source of international responsibility’ (1980) UN Doc. A/CN.4/318/Add.5–7, 15 [4]; James Crawford, ‘Second report on State responsibility’ (1999) UN Doc A/CN.4/498 and Add.1–4, 74 [296]. See further Trapp (n 72).

95  See Trapp (n 72) § IV (i).

96  ibid. To similar effect, see Federica Paddeu, ‘Use of Force against Non-state Actors and the Circumstance Precluding Wrongfulness of Self-Defence’ (2017) 30 Leiden Journal of International Law 93.

97  See Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory (Advisory Opinion) [2004] ICJ Reports 136, Separate Opinion of Judge Higgins, [33], questioning the ICJ’s having required that armed attacks be attributed to a state in its Nicaragua decision, given that there is nothing in the language of the Charter itself that restricts ‘armed attacks’ to uses of force by a state.

98  Trapp (n 72) § 4(i).

99  It should be noted that any de minimis threshold and the necessity and proportionality requirement would equally apply if attribution were a necessary condition for self-defence in response to armed attacks by NSAs.

100  Oil Platforms (n 75) [74].

101  See Oil Platforms (n 75) [76] (‘there is no evidence that the United States complained to Iran of the military activities of the platforms … which does not suggest that the targeting of the platforms was seen as a necessary act’). See also Yoram Dinstein, War, Aggression and Self-Defence (CUP 2005) 209–10.

102  See n 91.

103  ‘Iraq President Denies Offer to Extradite PKK Rebels’ Institut Kurde de Paris (24 October 2007) <http://www.institutkurde.org/en/info/latest/iraq-president-denies-offer-to-extradite-pkk-rebels-951.html>.

104  See n 44 and accompanying text.

105  See Trapp (nn 72, 78, 79).

106  Michael Howard, ‘Turkey Bombards Northern Iraq after Ambush’ The Guardian (London, 22 October 2007) <http://www.theguardian.com/world/2007/oct/22/turkey.iraq1>.

107  See nn 50 and 51 and accompanying text.

108  A contrario, see Nicaragua (n 73) [237]; DRC v Uganda (n 75) [147].

109  See n 27.

110  See Wall Advisory Opinion n 97, Separate Opinion of Judge Higgins [35].

111  See Tams and Devaney (n 65) 103.

112  Terry D Gill, ‘The Temporal Dimension of Self-Defense: Anticipation, Pre-emption, Prevention and Immediacy’ (2006) 11(3) Journal of Conflict and Security Law 361, 366.

113  See section I above.

114  See n 68 and accompanying text.

115  The United States, EU, and Turkey all characterize the PKK as a ‘terrorist organization’. See US Department of State, ‘Foreign Terrorist Organizations’ (2008) <http://www.state.gov/s/ct/rls/fs/08/l03392.htm>, 23; Council of the EU, Council Common Position 2008/586/CFSP of 15 July 2008 Updating Common Position 2001/931/CFSP on the Application of Specific Measures to Combat Terrorism and Repealing Common Position 2007/871/CFSP [2008] OJ L 188/71; (November 2007) 53 Keesing’s 48265.

116  See n 85.

117  See, in particular, DRC v Uganda (n 75), Separate Opinion of Judge Simma [4]–[15], lamenting the Court’s failure to do so.

118  See n 65 and accompanying text.

119  See n 67 and accompanying text.

120  See nn 59 and 62 and accompanying text.