Jump to Content Jump to Main Navigation
Signed in as:

Part 2 The Post-Cold War Era (1990–2000), 41 The Intervention in Bosnia and Herzegovina—1992–95

Pierre Klein

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, 2023. All Rights Reserved. Subscriber: null; date: 28 March 2023

Self-defence — Precedent — Regional organizations — UN Charter

(p. 495) 41  The Intervention in Bosnia and Herzegovina—1992–95

I.  Facts and Context

In 1991, Croatia and Slovenia’s unilateral declarations of independence initiated the Socialist Federative Republic of Yugoslavia’s (SFRY) disintegration, which quickly descended into violence. The Yugoslav Nations Army (JNA) intervened militarily in Slovenia and Croatia in an attempt to prevent secession.1 Years of war were to follow, later engulfing other former Yugoslav Republics, or parts thereof. The outbreak of an armed conflict within the country prompted the UN Security Council (UNSC) to swiftly characterize the situation in Yugoslavia as a threat to international peace and security and to implement a general embargo on deliveries of weapons and military equipment to the SFRY in September 1991.2 This measure, however, had no impact of the continuation of hostilities.

The UN was not the only international organization to be concerned with the situation. Indeed, faced with the prospect of Yugoslavia’s disintegration, but also that of the Soviet Union, in December 1991 the European Community (EC) adopted a Declaration on the ‘Guidelines on the Recognition of New States in Eastern Europe and in the Soviet Union’.3 The Declaration made recognition dependent upon compliance with basic legal principles such as ‘respect for the inviolability of all frontiers which can only be changed by peaceful means and by common agreement’ and made clear that ‘[t]he Community and its Member States [would] not recognize entities which are the result of aggression’. In a specific Declaration on Yugoslavia adopted at the same time, the EC and its member states expressed their will to ‘recognize the independence of all Yugoslav Republics’ fulfilling the conditions set out in the declaration, including in the area of human rights and rights of national or ethnic groups.4 Applications for recognition made by the Yugoslav Republics were to be submitted for advice to the Arbitration Commission established by the Community (‘Badinter Commission’).5

It is in that context that the authorities in Bosnia and Herzegovina voiced their intention to proclaim independence.6 This declaration of intention was met with the opposition of the vast majority of the Serbian population of that Republic. The Bosnian Serb Republic was established in reaction in January 1992, with the intention of remaining part of the Federal Republic of Yugoslavia.7 This move was however rejected by the authorities of Bosnia and Herzegovina. Following a referendum (identified by the Badinter Commission as a pre-condition for the recognition of the—future—state by the European (p. 496) Community8), Bosnia and Herzegovina proclaimed independence on 3 March 1992 and was recognized by the EC as an independent state on 6 April 1992. As from April 1992, the Bosnian Serb Army subjected the capital of Bosnia and Herzegovina, Sarajevo, to a siege that was to last forty-four months. The Yugoslav army officially left the territory of Bosnia and Herzegovina around mid-May 1992. A number of JNA units however stayed in Bosnia and Herzegovina and became part of the Bosnian Serb Army9 that remained involved in combats against the official Bosnian armed forces—but also against Bosnian Croat forces (HVO)—and committed various acts of—sometimes extreme—violence against civilian populations until the last months of 1995.10

In the first months of 1992, the UN increased its efforts to prevent the deterioration of the situation in the former Yugoslavia. A first step was the creation in February of the United Nations Protection Force (UNPROFOR), a peacekeeping operation with an initial strength of around 13,000 troops characterized as an ‘interim arrangement to create the conditions of peace and security required for the negotiation of an overall settlement of the Yugoslav crisis’.11 Then, in reaction to the extension of the war to Bosnia and Herzegovina, the UNSC repeatedly demanded the cessation of all forms of external interference in the new state12 and the disarmament of irregular forces present on its territory.13 The Council soon after condemned the Federal Republic of Yugoslavia (Serbia and Montenegro) (FRY) for failing to comply with the demands expressed in that resolution and, in late May 1992, it established a general embargo on trade and imposed various other restrictive measures on the FRY.14 This marked the beginning of the adoption of a—long—string of coercive measures by the Security Council, which quickly led to the use of military means in order to monitor the application of such measures—and later to enforce them. Operation Maritime Monitor was thus established by NATO in the following weeks, aimed at monitoring compliance with the measures adopted in Resolution 757 (1992) in the waters of the Adriatic Sea. This was effective between July and November 1992.15 The Western European Union (WEU) undertook a parallel operation for the same purposes in the Otranto Strait (Operation Sharp Vigilance).16

The Security Council went a step further when it opened the door to military measures to ensure the implementation of its decisions. This took the form of a combination of centralized and decentralized measures, the former being undertaken by UN forces under the direct control and authority of the organization, the latter being conducted by member states under the authorization given by the Security Council. The Council favored decentralization; hence, in August 1992 the Security Council called upon all States to ‘take all measures necessary to facilitate … the delivery … of humanitarian assistance in Sarajevo and wherever needed in other parts of Bosnia and Herzegovina’.17 The authorization to use (p. 497) force was deemed necessary by the Security Council as part of its efforts to restore peace and security in the country, in view of the strategies developed by some of the belligerents in order to achieve the displacement of civilian populations, of which the hindrance of humanitarian assistance was an essential component.18 A few weeks later, the Council authorized the enlargement of UNPROFOR’s mandate to include the use of ‘all necessary means’ to the same ends,19 thus authorizing the peacekeepers to use force for these purposes under the authority of the UN chain of command (centralized measures). The UN contingents, however, made very little use of this authorization in practice and very rarely resorted to force for the protection of humanitarian assistance.20

A further extension of the authorization to use force was soon to follow. In November 1992, the Security Council called upon all states to:

use such measures commensurate with the specific circumstances as may be necessary under the authority of the [Council] to halt all … maritime shipping in order to inspect and verify their cargoes and destinations and to ensure strict implementation of the provisions of resolutions 713 (1991) and 757 (1992).21

In other words, states were authorized to use coercive means to ensure that the maritime embargo ordered by the Security Council was complied with. It is, here again, through NATO that members states made use of that authorization. The organization’s role in that respect thus switched from monitoring to enforcement. It promptly put into place Operation Maritime Guard, entailing the implementation of measures of blockade and the inspection of more than 1,000 ships. This was succeeded by Operation Sharp Guard, between June 1993 and June 1996, which incorporated WEU forces and ships and placed them under a unified command with NATO.22 More than 6,000 ships were boarded and inspected in that context, more than 1,000 diverted for further inspection, and a dozen found to be in violation of the embargo.

The same pattern was followed with regard to the control of Bosnian airspace. In October 1992, in an attempt to curb the actions of Bosnian Serb forces, the Security Council imposed a ban on military flights in the airspace of Bosnia and Herzegovina, from which UNPROFOR flights were exempted.23 In this context as well, NATO played a role that was first limited to monitoring activities. The organization thus put into place Operation Sky Monitor, which registered several hundred violations of the flight ban. Poor compliance with the ban prompted the Security Council to give it some teeth a few months later. Indeed, in April 1993 it authorized member states:

acting nationally or through regional organizations or arrangements, to take, under the authority of the Security Council and in close coordination with the Secretary-General and UNPROFOR, all necessary measures in the airspace of the Republic of Bosnia and Herzegovina, in the event of further violations, to ensure compliance with the ban on flights … and proportionate to the specific circumstances and the nature of the flights.24

(p. 498) Here too, NATO’s role consequently evolved from monitoring to enforcement, through Operation Deny Flight. The most significant action taken in that context is the shooting down of four Bosnian Serb fighter planes by NATO aircrafts on 28 February 1994, which represented the first combat mission in NATO’s history.

In parallel, the Security Council gradually expanded the authorization to use force to ensure the protection of civilian populations in Bosnia and Herzegovina, in reaction to the practice of ‘ethnic cleansing’ used by some of the belligerents.25 A major step in that direction was the proclamation of safe areas ‘which should be free from armed attacks or any other hostile act’ in Srebrenica, Sarajevo, Tuzla, Zepa, Gorazde, and Bihac in April and May 1993.26 Shortly thereafter, in order to ensure full respect for the safe areas, the Security Council extended UNPROFOR’s mandate to enable it ‘to deter attacks against the safe areas, to monitor the cease-fire, to promote the withdrawal of military or paramilitary units other than those of the Government of the Republic of Bosnia and Herzegovina and to occupy some key points on the ground’.27 It also authorized UNPROFOR to act in self-defence by taking:

the necessary measures, including the use of force, in reply to bombardments against the safe areas by any of the parties or to armed incursions into them or in the event of any deliberate obstruction in or around those areas to the freedom of movement of UNPROFOR or of protected humanitarian convoys.28

Finally, the Council authorized member states to take all necessary measures, ‘through the use of air power in and around the safe areas to support UNPROFOR in the performance of its mandate’.29 Even though the wording of the resolution is rather convoluted—as shall be discussed at greater length below30—here again it is through both centralized and decentralized measures that the use of force is envisaged by the Council. NATO carried out a number of strikes against Bosnian Serb forces in the following weeks and months on that basis, at the request of UNPROFOR. However, far from bringing the hostilities to an end, this rather resulted in a further escalation of the conflict and an increase in the number of attacks against civilian populations, including in ‘safe areas’.31 In another adverse development, UNPROFOR contingents themselves later became a target and, on some occasions, were taken hostage by Bosnian Serb forces.32

It is, however, through the combination of stepped up negotiations and another round of military measures that the war in Bosnia and Herzegovina was ultimately brought to an end in 1995. In June 1995, the Security Council thus approved the creation of a 12,500-strong ‘rapid reaction capacity’ to reinforce UNPROFOR and to ‘enable [it] to carry out its mandate’33 and, in August and September, NATO conducted Operation Deliberate Force, aimed (amongst others) at ensuring the withdrawal of Bosnian Serb heavy weapons from the Sarajevo area and the lifting of the siege. Several strikes were conducted against (p. 499) Bosnian Serb forces during that period. The withdrawal of heavy weapons was achieved and strikes suspended in September 1995. In parallel, increased political pressure was exercised on Bosnian Serbs to take part in negotiations, which led to the conclusion of the Dayton Agreement on 21 November 1995.34 In order to ensure the full application of the agreement, the Security Council authorized the establishment of a multinational implementation force (IFOR), comprising of almost 60,000 NATO soldiers, in addition to troops from non-NATO countries.35 This constituted the first out-of-area land deployment in that organization’s history. As from that moment, IFOR took over from UNPROFOR. IFOR was endowed with significant enforcement powers, the Security Council having authorized member states ‘to take all necessary measures to effect the implementation of and to ensure compliance with Annex 1-A of the Peace Agreement’ and ‘to assist the force in carrying out its mission’.36 The authorization granted by the Security Council was extended until June 1998, when a ‘stabilization force’ (SFOR) succeeded IFOR.37 SFOR’s mission came to an end in 2004.

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

States have expressed very few reservations regarding the legality of the use of force in Bosnia and Herzegovina, due mostly to the fact that the military actions were undertaken with the UNSC’s authorization. No state has challenged the fact that situations of humanitarian emergency could be characterized as a threat to international peace and security and, as such, trigger the use of the Council’s coercive powers under Chapter VII, including coercion by military means. The only concerns expressed at the time appear to relate to the alleged lack of control by the Security Council over the exercise of the powers that had been delegated—some equating the authorization to a ‘blank cheque’.38 In the same vein, the conformity of some military actions undertaken by NATO with the resolutions authorizing the use of force has sometimes been disputed. Such was in particular the case for Operation Deliberate Force, in August and September 1995, deemed by Russia to exceed the bounds of the authorization given by the Security Council.39 However, such challenges were exceptional.

The ‘blank cheque’ argument was made in opposition to the majority view according to which significant safeguards had been put into place, with requirements such as close coordination with UN organs, a duty to report to the Council, and even, as in the case of Resolution 836 (1993), a ‘dual key’ system requiring approval from both UN and NATO for some military actions.40 Similarly, the position of the vast majority of states, both within and outside of the UN, was that actions undertaken by NATO were in compliance with the framework set by the Security Council resolutions. The position expressed by France in 1994 is illustrative in that regard, when it stated that ‘the North Atlantic (p. 500) Council’s decisions need not be submitted to the Security Council for a fresh decision’ since they ‘are clearly and unambiguously within the ambit of Security Council resolutions 824 and 836 on safe areas’.41

III.  Questions of Legality

If the question of the use of military means to enforce UNPROFOR’s mandate in Bosnia and Herzegovina gave rise to numerous discussions and debates, these were much less concerned with issues of legality as such than with considerations of efficacy and appropriateness of such measures in that context.42 Concerns could, however, have been raised as to the Security Council’s power to authorize the use of force under such circumstances. Indeed, while the authorization to use force given by the Council to states or groups of states was not an entirely new phenomenon in 1992, it had only concerned a previous situation in which a state had been the victim of an armed attack by another state.43 In the Bosnian case, the Security Council gave such an authorization in a very different context and for purposes that had nothing to do with repelling an aggression. Humanitarian purposes were indeed the paramount concern when the Council authorized states and groups of states to use ‘all necessary means’ for the protection of humanitarian assistance in August 199244 and of the designated ‘safe areas’ in June 1993.45 This, however, did not amount to any kind of infringement of that organ’s powers under the Charter, since those measures have consistently been framed as a response to a threat to peace and security arising from the situation in Bosnia and Herzegovina. Both resolutions are also significant from another perspective. They indeed confirm that states viewed passage through the Security Council—and Chapter VII procedures—as a clear prerequisite for the use of forcible measures against states or non-state actors in the context of humanitarian emergencies. In that sense, the precedent of Bosnia and Herzegovina—as that of Somalia at the same moment46—can be seen as a repudiation of doctrines proclaiming the right—or duty—of states to intervene unilaterally in such circumstances.47 Far from giving any credit to such unilateral approaches, it rather evidences the existence in contemporary international law of mechanisms allowing for the use of coercive—including military—measures for such purposes. It should be added that the use of force in the context of the conflict in Bosnia and Herzegovina appeared all the less problematic in legal terms that military operations conducted by external actors on that state’s territory also benefited from the latter’s authorities’ consent.48

The only doubts that appear to have been expressed in legal writings concerning the legality of these interventions relate, here too, to the Security Council’s delegation of the power to use force. Some authors have thus relayed the ‘blank cheque’ argument,49 (p. 501) while others argued that the reporting (and other control) mechanisms put in place by Resolution 770 were sufficient to prevent the problems that had been raised by the implementation of Resolution 678 in the context of the Iraq war in 1991.50

In any event, there appears to be wide consensus that the precedent illustrates the admission by NATO that an authorization from the Security Council was required for the Alliance to resort to coercive measures involving the use of force outside of situations of self-defence51—a position that, with one significant exception,52 may be said to have endured over time. Further problems of legality arose from the fact that this was the first ‘out-of-zone’ intervention by NATO, in a situation that did not involve self-defence, while the Organization’s constituent instrument only provided for the use of force in (collective) self-defence, in a limited geographical area.53 Authors have, however, pointed out that such extensions of the organization’s missions were based on new ‘strategic concepts’ adopted by consensus by all members states, that amounted to informal amendments of the constituent instrument and therefore did not give rise to issues of legality under international law.54

The intervention in Bosnia and Herzegovina can be seen as a kind of experimentation chamber for possibilities to use force in the context or in support of UN peacekeeping operations in the period immediately following the end of the Cold War. These possibilities included both measures taken in self-defence (as this concept is understood in the specific context of UN peacekeeping) and coercive military measures under Chapter VII of the Charter, in cooperation with regional organizations or arrangements.

1.  Self-defence

Even though UN peacekeeping operations have very early on been characterized as non-coercive—being based on host state consent—55 the possibility that peacekeepers may resort to armed force in self-defence was recognized from the outset. The concept was initially envisaged restrictively, covering the use of force exclusively to repel attacks against the peacekeeping force and its members (‘personal self-defence’).56 Nevertheless a broader definition of self-defence soon emerged in that context, including the use of force in defence of the mission’s mandate.57 While these rules have in the past been articulated by (p. 502) the Secretary-General upon definition of the missions’ concept, it is the Security Council that (re-)affirmed them in relation to crucial aspects of UNPROFOR’s mandate, such as the protection of the ‘safe areas’ it had identified in Bosnia and Herzegovina.58 For many commentators, this signalled a deliberate move—often seen as problematic59—from the traditional, consent-based, and ‘cooperative’ concept of peacekeeping operations to a type of intervention that would be better characterized as ‘peace-enforcement’ or ‘robust peacekeeping’.60 From then on, peacekeeping operations have indeed frequently been endowed with more coercive powers for the execution of parts of their mandate, in particular for the protection of civilian populations.61 This precedent at any rate confirms that the notion of self-defence, as understood and applied in the context of UN peacekeeping operations, has—very—little to do with the principle enshrined in Article 51 of the UN Charter, whose scope and interpretation cannot be considered as being in any way affected by that particular practice.62

2.  Coercive military measures under Chapter VII of the UN Charter in cooperation with regional organizations or arrangements

As noted above,63 the UN intervention in Bosnia and Herzegovina may certainly be seen as a crucial milestone in the development of a practice entailing the use of coercive military measures for humanitarian purposes. Beyond this, the precedent discussed here is also remarkable to the extent that it provides a case study on the cooperation between the UN and regional organizations or groupings of states for the maintenance of international peace and security, including as far as the use of military force is concerned. Resolutions 770 (1992) and 836 (1993) authorize ‘States [acting] nationally or through regional agencies or arrangements’ to use force in order to carry out the resolutions’ decisions’. The same wording is used in Resolutions 787 (1992) and 816 (1993), authorizing the adoption of necessary measures for the enforcement of the maritime embargo against the FRY and of the flight ban over the territory of Bosnia and Herzegovina respectively.64 It is indeed ‘through regional agencies or arrangements’—chiefly NATO and, to a more limited extent, WEU—that states have enacted—or attempted to enact65—those authorizations. This pattern has since been followed in a number of situations where the Security Council authorized such ‘regional agencies or arrangements’ to make use of coercive military measures for the maintenance of international peace and security.66

IV.  Conclusion: Precedential value

Exemplary as it may be from an institutional perspective, the authorization to use force in the context of the conflict in Bosnia and Herzegovina raised very serious concerns as to its efficiency and appropriateness. What most states and commentators pointed to was indeed the lack of efficacy of UNPROFOR’s action—and its global failure to fulfil its (p. 503) mandate—in spite of the fact that the mission itself had been explicitly endowed with the power to use force and that all states had been authorized to use military means to support the implementation of the mandate. The very harsh criticism expressed67 in that respect focused mainly on two issues. The first relates to the nature of UN peacekeeping. Critics argued that UNPROFOR’s experience showed that the shift from ‘classical’ cooperative peacekeeping to enforcement operations threatened the very concept of peacekeeping and proved unworkable in practice. A strong reluctance on the part of key military actors in the mission has also been emphasized in that respect, with the prevalence of the idea that the UN force ‘could somehow implement an enforcement mandate through the peacekeeping techniques of consensus and compromise’.68 The blurring of the distinction between the two types of actions led to situations where UN peacekeepers in Bosnia and Herzegovina became identified as belligerents and targeted as such, thereby compromising the fulfilment of the mission’s mandate.69 Enforcement quickly became illusory70 and the—few—military actions undertaken in support of UNPROFOR were aimed at ensuring the safety of the peacekeepers rather than that of the populations these were supposed to protect.71 Profound ambiguities persisted until the end, with high officials of UNPROFOR still asserting in 1995 that their mission was ‘purely peacekeeping’.72 Such conceptions ultimately had an impact on the action undertaken by NATO in support of the UN mission, which often amounted more to peacekeeping than to actual enforcement.73

The second main obstacle identified by commentators is the lack of political will to ensure the implementation of the coercive mandate(s) issued by the Security Council—or at least of some of these.74 The execution of several aspects of these mandates would indeed have required significant increases in the number of troops deployed on the ground and a willingness to accept possibly higher casualties—commitments that most prominent troop contributing nations were visibly not eager to make.75

The intervention in Bosnia and Herzegovina may thus be seen, on the one hand, as a showcase for the possibilities to resort to force in conformity with the UN Charter in the context of peacekeeping operations—and more specifically, for mainly humanitarian purposes—ranging from ‘peace-enforcement’ to the use of military coercion by states or groups of states in support of such operations. However, on the other hand, this precedent also evidences the limitations that may hinder the implementation of such coercive mandates, in both conceptual and political terms. It certainly epitomizes the difficulties encountered by the UN in its attempts to face the many challenges that arose in various parts of the world after the end of the Cold War and it may be said that some of the wounds opened then are not fully healed yet, more than twenty years later.76


1  See, eg, ‘The Conflict in Yugoslavia—A Chronology’ in Marc Weller and Daniel Bethlehem (eds), The Yugoslav Crisis in International Law, vol I (CUP 1997) xxvi.

2  UNSC Res 713 (25 September 1991) UN Doc S/RES/713 (1991), [6].

3  16 December 1991, reprinted in Marc Weller (ed), The Crisis in Kosovo 1989-199I, Documents & Analysis Publishing (CUP 1999) 80.

4  ibid 81.

5  ibid.

6  ‘The Conflict in Yugoslavia —A Chronology’ (n 1) xxx–xxxi.

7  ibid xxxiii.

8  Opinion n° 4 (Recognition of Bosnia-Hercegovina), 11 January 1992, 92 ILR at 173.

9  See, eg, UN Secretary General’s Report of 24 April 1992, UN Doc S/23844, [16].

10  See below—the most significant of these was of course the massacre of more than 8,000 persons in Srebrenica, characterized as an act of genocide by both the International Criminal Tribunal for the former Yugoslavia (Blagojevic, case IT-02-60-T, Judgment of 17 January 2005, at [674]) and the International Court of Justice (Application of the Convention for the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v Serbia and Montenegro) (Judgment) [2007] ICJ Rep 2007 at 166, [297]).

11  UNSC Res 743 (21 February 1992) UN Doc S/RES/743, [4] and [5].

12  Bosnia and Herzegovina was admitted as a member of the United Nations in May 1992 (UNGA Res 46/237 (22 May 1992) UN Doc A/RES/46/237).

13  See initially UNSC Res 752 (15 May 1992) S/RES/752 (1992), [3] and [5].

14  UNSC Res 757 (30 May 1992) UN Doc S/RES/757 (1992), [1] and [4]f.

15  NATO Unclassified, ‘NATO’s operations, 1949-Present’ <http://www.shape.nato.int/resources/21/nato%20operations,%201949-present.pdf>.

16  ‘The Conflict in Yugoslavia—A Chronology’ (n 1) xxxvii.

17  UNSC Res 770 (13 August 1992) UN Doc S/RES/770 (1992), [2].

18  See, eg, Report of the Secretary General pursuant Resolution 752 (1992) (25 May 1992) UN Doc S/24000, [18].

19  UNSC Res 776 (14 September 1992) UN Doc S/RES/776 (1192), [2].

20  See, eg, Marc Weller, ‘Peacekeeping and Peace-enforcement in the Republic of Bosnia and Herzegovina’, (1996) Zeitschrift fur auslandiches öffentliches Recht und Völkerrecht 70, 96.

21  UNSC Res 787 (16 November 1992) UN Doc S/RES/787 (1992), [12].

23  UNSC Res 787 (9 October 1992) UN Doc S/RES/781 (1992), [1].

24  UNSC Res 816 (16 April 1993) UN Doc S/RES/816 (1993), [4].

25  See above and, for an initial condemnation, UNSC Res 787 (n 23) [2].

26  UNSC Res 816 (n 24) [1] and UNSC Res 824 (6 May 1993) UN Doc S/RES/824, [1]. The ‘safe area’ concept was based on a proposal put forward by France (see Note verbale dated 93/05/19 from the Permanent Representative of France to the United Nations addressed to the President of the Security Council, UN Doc S/25800, [1]).

27  UNSC Res 836 (4 June 1993) S/RES/836 (1993) [5].

28  ibid [9].

29  ibid [10].

30  See below section IV.

31  See, eg, UNSC Res 913 (22 April 1994) UN Doc S/RES/913 (1994) (condemning ‘the shelling and attacks by the Bosnian Serb forces against the safe area of Gorazde’ at [3]).

32  See, eg, UNSC Res 987 (19 April 1995) UN Doc S/RES/987 (demanding the end of ‘acts of intimidation or violence against UNPROFOR and its personnel’, at [1]); Weller (n 20) 140.

33  UNSC Res 998 (16 June 1995) UN Doc S/RES/998, [9] and [10].

34  General Framework Agreement for Peace in Bosnia and Herzegovina, 35 ILM 223 (1996). The agreement was officially signed in Paris on 14 December 1995.

35  UNSC Res 1031 (15 December 1995) UN Doc S/RES/1031 (1995), [14]ff.

36  ibid [15]–[17].

37  UNSC Res 1088 (12 December 1996) UN Doc S/RES/1088 (1996); UNSC Res 1174 (15 June 1998) UN Doc S/RES/1174 (1998).

38  See the references in Weller (n 20) 98.

39  See the references in ibid 159.

40  See, eg, Olivier Corten and Pierre Klein, ‘L’autorisation de recourir à la force à des fins humanitaires: droit d’ingérence ou retour aux sources?’ (1993) European Journal of International Law 506, 527ff; Ugo Villani, ‘Les rapports entre l’ONU et les organisations régionales dans le domaine du maintien de la paix’ (2001) 290 Hague Collected Courses 382–83.

41  In ‘Pratique française du droit international’ (1994) 40 Annuaire français de droit international 1039, as translated and quoted in Olivier Corten, The Law Against War (Hart Publishing 2010) 539. Emphasis in original; see also ‘Netherlands State Practice’ (1994) 25 Netherlands Yearbook of International Law 458 and ‘Contemporary Practice of the United States’ (1994) 88 American Journal of International Law 522–25.

42  For more on these, see below section IV.

43  See Chapter 38, ‘The Gulf War—1990–91’ by Erika de Wet in this volume.

44  UNSC Res 770 (n 17).

45  UNSC Res 836 (n 27).

46  See Chapter 40, ‘The Intervention in Somalia—1992–95’ by Terry D Gill and Kinga Tibori-Szabó in this volume.

47  See, eg, Corten and Klein, ‘L’autorisation de recourir à la force …’ (n 40) 526.

48  On this see, eg, Weller (n 20) 149.

49  See, eg, Inge F Dekker and Eric P J Myjer, ‘Air Strikes on Bosnian Positions: Is NATO also Legally the Proper Instrument of the UN?’ (1996) Leiden Journal of International Law 411, 415; Nicholas Tsagourias and Nigel White, Collective Security—Theory, Law and Practice (CUP 2013) 253.

50  See, eg, Corten and Klein, ‘L’autorisation de recourir à la force … ’ (n 40) 530; for more on this, see Chapter 38, ‘The Gulf War—1990–91’ by Erika de Wet in this volume.

51  For more on this and references to primary sources see, eg, Rosalyn Higgins, ‘Some Thoughts on the Evolving Relationship Between the Security Council and NATO’ in Mélanges Boutros-Ghali (Bruylant 1998) 523; Barbara Delcourt and François Dubuisson, ‘Contribution au débat juridique sur les missions “non-article 5” de l’OTAN’ (2002) Revue belge de droit international 448–49.

52  See Chapter 47, ‘The Kosovo Crisis—1999’ by Daniel Franchini and Antonios Tzanakopoulos in this volume; the intervention of NATO in Libya (2011) also proved controversial since it was widely alleged that while NATO’s use of force in that country was based on an authorization given by the Security Council, the organization had exceeded the terms of the UNSC resolutions (see Chapter 56, ‘The NATO Intervention in Libya—2011’ by Ashley Deeks in this volume).

53  See Articles 5 and 6 of the North Atlantic Treaty of 4 April 1949; see also, eg, Dekker and Myjer (n 49) 416.

54  See, eg, Delcourt and Dubuisson (n 51) 444–45.

55  Certain Expenses of the United Nations (Article 17, paragraph 2, of the Charter) (Advisory Opinion) [1962] ICJ Rep 1962 at 177; the opinion was approved by the General Assembly in Resolution 1854 (XVII) (19 December 1962) UN Doc A/RES/1854 (XVII).

56  See, eg, Katherine E Cox, ‘Beyond Self-Defence: UN Peacekeeping Operations and the Use of Force’ (1998–99) 27 Denver Journal of International Law & Policy 229, 250, referring to the initial formulation of the concept for UNEF I; Olivier Corten and Pierre Klein, ‘Action humanitaire et Chapitre VII: la redéfinition du mandat et des moyens d’action des Forces des Nations Unies’ (1993) Annuaire français de droit international 105, 121.

57  Cox (n 56) 252, referring to the reformulation of the principle for UNFICYP and, later, UNEF II.

58  See above UNSC Res 836 (n 27) [9].

59  For more on this see below.

60  Cox (n 56) 255; Weller (n 20) 100; Michael Bothe, ‘Peacekeeping’ in Bruno Simma et al (eds), The United Nations CharterA Commentary (3rd edn, OUP 2012) [16]. Tsagourias and White even use the terms ‘belligerent peacekeeping’ (n 49) 251.

61  Bothe (n 60) [16]: see, eg, MONUC, ONUCI, UNMIS (UNSC Res 1996 (8 July 2011) UN Doc S/RES/1996 (2011), [4]).

62  Cox for instance raises the question of the way in which the proportionality and necessity principles come into play in the context of extended self-defence in peacekeeping operations (n 56) 270.

63  See above section III.

64  See above.

65  For more on this, see below.

66  See, eg, UNSC Res 1244 (10 June 1999) S/RES/1244 (1999) (NATO–KFOR in Kosovo) or UNSC 1769 (31 July 2007) S/RES/1769 (2007) (African Union, in the context of UNAMID in Darfur).

67  Not least by the Government of Bosnia and Herzegovina itself (see, eg, the references in Weller (n 20) 149 and 156–57).

68  Weller (n 20) 149.

69  See, eg, Tsagourias and White (n 49) 262; in more general terms, Scot Sheeran, ‘The Use of Force in United Nations Peacekeeping Operations’ in Oxford Handbook on the Use of Force (OUP 2015) 338.

70  One author speaks of a ‘phantom enforcement operation’ (Weller (n 20) 177); see also Higgins (n 51) 524–25.

71  Rosalyn Higgins, ‘Peace and Security—Achievements and Failures’ (1995) European Journal of International Law 457; Weller (n 20) 174.

72  Quoted by Weller (n 20) 139.

73  Weller (n 20) 146; Higgins, ‘Some Thoughts on the Evolving Relationship … ’ (n 51) 524.

74  No such problems arose for the enforcement of the maritime embargo against the FRY, for instance.

75  See, eg, Corten and Klein, ‘Action humanitaire et Chapitre VII … ’ (n 56) 128 (and the accompanying references); Weller (n 20) 144.

76  One may think in particular of the litigation against both the UN and the Netherlands before the Dutch Courts for failure to ensure protection of the civilian populations in the ‘safe areas’; see, eg, Supreme Court of the Netherlands, The State of the Netherlands v H. Nuhanovic, case n° 12/03329, 6 September 2013; and The State of the Netherlands v M. Mustafic, case n° 12/03329, 6 September 2013.