The prohibition of the use of force

defence of what a Boundary Commission subsequently decided to be its own territory.6

However, the most basic disagreement concerns the significance of the last part of Article 2(4). This controversy came dramatically to the fore in the use of force by NATO in Kosovo in 1999. States and commentators expressed their fundamental disagreements about the legality of this intervention in terms of Article 2(4). Some claimed that a new right to humanitarian intervention was emerging; others that the NATO action was a flagrant breach of the UN Charter.

The current debate is a reincarnation of earlier disagreements on the interpretation of Article 2(4). Here these will be set out in outline only. Writers disagreed as to whether Article 2(4) reflected existing customary international law or whether it was in 1945 a radical departure from previous customary law, to be narrowly interpreted. The controversy centred on the second part of Article 2(4): should the words ‘against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations’ be construed as a strict prohibition on all use of force against another state, or did they allow the use of force provided that the aim was not to overthrow the government or seize the territory of the state and provided that the action was consistent with the purposes of the UN?7 Many US commentators argued during the Cold War that the interpretation of Article 2(4) depended on the effective functioning of the UN collective security system, and therefore that the inability of the Security Council to act because of the veto of the five permanent members meant that Article 2(4) should be read to allow the use of force to further ‘world public order’ or the principles and purposes of the UN.8

For many years this doctrinal disagreement was of limited practical significance in that states themselves rarely made any attempt to interpret Article 2(4) in this narrow fashion; they did not in fact claim that their use of force was justified because it did not aim to seize the territory or overthrow the government of another state or because the UN system was not working. They did not rely on a narrow interpretation of Article 2(4) in order to claim a legal right to use force for humanitarian intervention or to overthrow governments in the name of democracy or some other political system. The argument of the UK in the Corfu Channel case remained a relatively isolated example; it claimed that its use of forcible intervention in Albanian waters to recover evidence that might indicate who was responsible for the destruction of two British warships by mines did not violate Article 2(4) because its action did not threaten the territorial integrity or the political independence of Albania. The famous rejection of this argument by the ICJ has been interpreted in fundamentally divergent ways, either as a complete rejection of the narrow interpretation of Article 2(4) or as a more limited rejection of the UK claim on the particular facts. The Court said it ‘can only regard the alleged right of intervention as the manifestation of a policy of force such as has in the past given rise to most serious abuses and such as cannot find a place in international law. It is still less admissible in the particular form it would take here—it would be reserved for the most powerful states.’ 9

Similarly there were indications that Israel also took a narrow interpretation of Article 2(4) over the Entebbe incident in 1976; when hijackers diverted an aircraft bound for Tel Aviv to Uganda, Israeli forces mounted a successful rescue operation in Uganda. The main argument of Israel in the Security Council was expressly based on self-defence of its nationals, but it also put forward an interpretation of Article 2(4) by the writer O’Connell as allowing the limited use of force when UN machinery was ineffective.10 This line was not taken up by other states in the Security Council debate, except perhaps by the USA in its passing reference to the breach of Uganda’s sovereignty as only temporary.11 The Israeli argument on Article 2(4) was expressly rejected by Sweden; it said, ‘The Charter does not authorize any exception to this rule except for the right of self-defence and enforcement measures undertaken by the Council under Chapter VII of the Charter. This is no coincidence or oversight. Any formal exceptions permitting the use of force or of military intervention in order to achieve certain aims, however laudable, would be bound to be abused, especially by the big and strong, and to pose a threat, especially to the small and weak.’12 The overwhelming majority of states speaking in the debate regarded Israel’s action as a breach of Article 2(4). Those who did not condemn Israel did not expressly defend the legality of its action in terms of a narrow interpretation of Article 2(4).

More significantly, when the USA justified its invasion of Grenada in 1983 it suggested in the Security Council that Article 2(4) should not be seen in isolation; ‘the prohibitions against the use of force in the Charter are contextual, not absolute. They provide justification for the use of force in pursuit of other values also inscribed in the Charter, such values as freedom, democracy, peace.’13 But earlier in the debate the USA had relied on the right to protect its nationals in danger and on an invitation by the Governor-General of Grenada to justify its action. Thus in the Entebbe and Grenada incidents the narrow interpretation of Article 2(4) as a less than absolute prohibition of the use of force was not crucial to the state using force: the USA and Israel also put forward other arguments to justify their actions, and the interpretation of Article 2(4) played only a subsidiary and not a decisive role in determining the legality of the intervention. The question of the interpretation of Article 2(4) plays a more decisive role in the debate over humanitarian intervention.


Until recently unilateral humanitarian intervention was not put forward as a legal doctrine by states. The Indian action in Bangladesh (1971) which helped the people to secure independence from Pakistan and to end repression,14 the Tanzanian action in Uganda (1979) which led to the overthrow of Idi Amin,15 and the Vietnamese invasion of Cambodia (1978) which led to the overthrow of Pol Pot16 were not in fact justified by India, Tanzania and Vietnam on the basis of humanitarian action; rather, the states using force focused mainly on self-defence. The first two episodes avoided condemnation by the Security Council or the General Assembly,17 but the last, although it was at least as persuasive a case for humanitarian intervention, divided states partly on Cold War lines (and partly because of the regional rivalry between Vietnam and China) and was repeatedly condemned by the General Assembly.18 Many states, including France and the UK, said that violations of human rights could not justify the use of force.19

During the Cold War it was writers rather than states that argued in favour of the doctrine of humanitarian intervention as a justification for the use of force by states.20 In 1984 the UK Foreign and Commonwealth Office had expressed considerable doubt as to the existence of such a doctrine, saying that it was very controversial: the state practice to which advocates of the right of humanitarian intervention had appealed provided an uncertain base on which to rest such a right. Not least this was because history had shown that humanitarian ends were almost always mixed with other, less laudable motives for intervening, and because often the humanitarian benefits of an intervention were either not claimed by the intervening state or were only put forward as an ex post facto justification of the intervention. In fact ‘the best case that can be made in support of humanitarian intervention is that it cannot be said to be unambiguously illegal’.21 The absence of the express invocation of the right by states did not, however, deter some writers from arguing that all or some of the above episodes were actually part of state practice supporting a legal right to humanitarian intervention because the states using force should have or could have used this justification.22

These writers ignored the General Assembly resolutions on the use of force which outlawed forcible intervention in absolute terms. The Friendly Relations Declaration excludes the right to intervene and makes no provision for humanitarian intervention.23 The Definition of Aggression provision that ‘no consideration of whatever nature, whether political, economic, military or otherwise, may serve as a justification for aggression’ also supports this.24 These writers also explained away the rejection of forcible humanitarian intervention by the ICJ in the Nicaragua case as either simply mistaken or limited to the particular facts.25 The USA did not actually invoke the doctrine of humanitarian intervention to justify its support for the contras in their attempt to overthrow the government of Nicaragua, or to justify its direct use of force in mining Nicaraguan ports and bombing oil installations. The Court nevertheless considered whether the protection of human rights might provide a legal justification for the US use of force. The Court said, ‘While the USA might form its own appraisal of the situation as to respect for human rights in Nicaragua, the use of force could not be the appropriate method to monitor or ensure such respect. With regard to the steps actually taken, the protection of human rights, a strictly humanitarian objective, cannot be compatible with the mining of ports, the destruction of oil installations, or again with the training, arming and equipping of the contras.’ 26 This can be seen as either a complete rejection of any right to use force to protect human rights or as merely a finding that the particular US action did not further any humanitarian objective.27

Recent years have seen a shift in state practice and a polarization between NATO states on the one hand and Russia, China and the Non-Aligned Movement on the other. Certain states have now been prepared to rely more openly on a legal doctrine of humanitarian intervention. The first signs of this emerged in the UK justification of the operations which it undertook with the USA and France to protect the Kurds and Shiites in Iraq after the 1991 Iraq/Kuwait conflict.28 During the UN-authorized operation to drive Iraqi forces out of Kuwait the Kurds and Shiites had been encouraged by the coalition states to rebel against the government, but the ceasefire resolution passed by the Security Council made no provision for the protection of the Kurds in northern Iraq and the Shiites in the south. When the operation to drive Iraqi forces out of Kuwait was over, the government of Iraq turned on the Kurds and Shiites. At first the members of the Security Council treated this as an internal question for Iraq, but under pressure from France the Security Council returned to the matter and passed Resolution 688 (1991).29 This called on Iraq to end the repression of its civilian population and to allow access to international humanitarian organizations, but it did not authorize the use of force to help the Kurds and Shiites. The resolution was not passed under Chapter VII and it expressly recalled Article 2(7) of the UN Charter prohibiting the UN from intervention in matters within domestic jurisdiction. Even so, those states which abstained or voted against the resolution did so because they saw it as an illegitimate intervention in Iraqi internal affairs and not a matter for the Security Council.

Despite the absence of express authority from the Security Council, the USA, the UK and France nevertheless forcibly intervened to protect the Kurds and Shiites in Iraq. They proclaimed safe havens and forced Iraqi troops to leave these areas. They did not offer any explicit legal justification for their action; they did not put forward in the Security Council the doctrine of humanitarian intervention as the justification for their action. Indeed, they did not at this time seem to feel the need to put forward any legal justification. This may be seen as an indication that there was no well-established doctrine of humanitarian intervention at that time. The operation was not condemned by the Security Council or the General Assembly. The USA, the UK and France subsequently proclaimed no-fly zones over north and south Iraq and continued to patrol Iraqi airspace in order to protect the Kurds and Shiites.30 This was also done without Security Council authority. When Iraq lodged protests with the Security Council the USA, the UK and France replied by saying that their measures were designed to prevent Iraqi repression. They also said that they were acting in support of Resolution 688 (1991). This apparent attempt to bring their action within an implied authorization by Security Resolution in the absence of any express authorization provided a pattern that was to be followed in the future.31

Later the UK did openly espouse the doctrine of humanitarian intervention. It modified its earlier position that the most that could be said about humanitarian intervention was that it was ‘not unambiguously illegal’. From August 1992 it moved gradually towards an expression of the doctrine of humanitarian intervention as the justification for the actions in Iraq. It did so, not in the Security Council, but in response to domestic pressure, in statements and publications in the UK. The Foreign and Commonwealth Office said that international law develops to meet new situations. ‘We believe that international intervention without the invitation of the country concerned can be justified in cases of extreme humanitarian need. This is why we were prepared to commit British forces to Operation Haven, mounted by the coalition in response to the refugee crisis involving the Iraqi Kurds. The deployment of these forces was entirely consistent with the objectives of SCR 688 (1991).’32 But it did not explain how this alleged change in the law had come about. If Article 2(4) of the UN Charter is a dynamic provision open to changing interpretation over time, what developments in fact justified a new interpretation? The UK later elaborated on the doctrine of humanitarian intervention, putting forward conditions which could govern its use. First, there should be a compelling and urgent situation of extreme humanitarian distress which demanded immediate relief; the other state should not be able or willing to meet the distress and deal with it; there should be no practical alternative to intervening in order to relieve the stress, and also the action should be limited in time and scope.33 This UK espousal of the doctrine of humanitarian intervention seems to have been the first open support by a state since the establishment of the UN. The USA, in contrast, did not put forward this doctrine, preferring to rely on implied authorization by the Security Council.34

Confrontations between Iraq and the coalition planes patrolling the no-fly zones occurred in 1991 and 1992; they escalated in 1993 when the coalition forces mounted a major operation against Iraqi missile sites and again in 1999 when a long series of confrontations occurred. The actions in 1999 went further than previous use of force in that the coalition rules of engagement were expanded to cover not only response to an armed attack, but also pre-emptive action against Iraqi missile sites and command and control centres.35 The legal justifications put forward by the USA and the UK assumed the legality of the no-fly zones; they said that their pilots had the right of self-defence to cover action against Iraqi planes and missile sites. The protests of Iraq did not lead to condemnation by the Security Council or the General Assembly. But the escalation of activity in 1999 was discussed by the Security Council; Russia and China condemned the use of force in the no-fly zones by the US and UK aircraft.36 The UK replied that its operations were purely reactive and not aggressive. The no-fly zones were necessary both to limit Iraq’s capacity to oppress its own people and to monitor its compliance with obligations. The USA agreed with this rationale.37 The preference of the UK and the USA not to enter into discussion of the legal basis of the no-fly zones, but to focus where possible on claims to self-defence, indicates at the least an awareness that the doctrine of humanitarian intervention remained controversial.

Further polarization of states over the no-fly zones occurred as the activities of the USA and the UK continued.38 There was open opposition by many states; France abandoned not only its participation but also its support; there was little, if any, open support for the legality of the ‘coalition’ operations on the basis of humanitarian intervention. It is not clear that these actions satisfied the criteria for humanitarian intervention set out by the UK in 1992.39 The actions could not convincingly be described as multilateral, despite the care the USA and the UK took to speak of ‘coalition’ action.40 They were ‘limited in time and scope’ only in the sense that individual operations were so limited; the maintenance of the no-fly zones lasted for over ten years. Most important, the question was raised as to how far the USA and the UK were genuinely motivated by humanitarian concern, or whether their true aim was the overthrow of Saddam Hussein, an aim openly avowed by the USA but disavowed by the UK.41 In the months leading up to the invasion of Iraq in March 2003 there were accusations that the operations in Iraq were designed not for humanitarian protection, but to weaken Iraqi air defences to prepare for the eventual invasion of 2003.42


The NATO action in Kosovo in 1999 revealed even more clearly the fundamental split as to the legality of humanitarian intervention.43 NATO forces undertook Operation Allied Force in response to the repression of ethnic Albanians in the region of Kosovo by the federal government of Yugoslavia under President Milosevic.44 The legal arguments of states for and against this action will be discussed in detail in order to illuminate the doctrinal debate about Article 2(4), its relation to Chapter VII, and the practical importance of this debate. It was clear that this bombing campaign against Yugoslavia in protection of the Kosovo Albanians marked a new departure for NATO, which was moving away from its original role as an organization for collective self-defence. With the end of the Cold War it had sought a new role for itself; from 1990 it had begun to redefine itself.45 It had agreed on the need to transform the Atlantic Alliance ‘to reflect the new, more promising era in Europe’. It adopted a new strategic concept in 1991. This said that risks to Allied security were less likely to result from calculated aggression against the territory of the Allies, but rather from the adverse consequences of instabilities that may arise from the serious economic, social and political difficulties, including ethnic rivalries and territorial disputes which are faced by many countries in Central and Eastern Europe. These tensions could lead to crises inimical to European stability and even to armed conflicts which could involve outside powers or spill over into NATO countries, having a direct effect on the security of the Alliance. Moreover Alliance security must also take account of the global context; security interests could be affected by other risks including proliferation of weapons of mass destruction, disruption of the flows of vital resources and actions of terrorism and sabotage. Accordingly NATO would have to be prepared to undertake management of crises. In pursuance of this new role NATO became involved in the 1991–95 conflict in the former Yugoslavia and used force other than in collective self-defence. But in that conflict its member states were specifically authorized to use force by the Security Council.46

After this action further changes were made to NATO’s strategic concept. The 1991 new strategic concept had still emphasized that ‘the Alliance is purely defensive in purpose’. This phrase has disappeared from the new strategic concept adopted in 1999. NATO was now not only to ensure the defence of its members but also to contribute to peace and security in the ‘Euro-Atlantic region’. NATO would undertake new missions, including conflict prevention and crisis management. This redefinition of NATO was made specifically in response to the events in Kosovo. The member states, in announcing the 1999 strategic concept, explained that:

        The continuing crisis in and around Kosovo threatens to further destabilise areas beyond the Federal Republic of Yugoslavia. The potential for wider instability underscores the need for a comprehensive approach to the stabilisation of the crisis region in South-Eastern Europe. We recognise and endorse the crucial importance of making South-Eastern Europe a region free from violence and instability. A new level of international engagement is thus needed to build security, prosperity and democratic civil society, leading in time to full integration into the wider European family.47

Nevertheless, when NATO resorted to force to protect ethnic Albanians in Kosovo, there was still some ambivalence in the official NATO statements as to the precise legal justification for its action against Yugoslavia. NATO did not clearly and expressly invoke humanitarian intervention as a legal doctrine; the initial authorization by the North Atlantic Council of air strikes in January 1999 said only that the crisis in Kosovo was a threat to the peace and security of the region; the NATO strategy was to halt the violence in Kosovo and thus avert a humanitarian catastrophe.48 When Operation Allied Force actually began in March 1999 the NATO justification focused primarily on moral and political rather than expressly legal justifications for the action. The Secretary-General of NATO said that all efforts to achieve a negotiated, political solution to the Kosovo crisis had failed and they were taking action to support the political aims of the international community. The military aim was to disrupt the violent acts being committed by the Serb army and to weaken their ability to cause further humanitarian catastrophe. They wished thereby to support international efforts to secure Yugoslav agreement to an interim political settlement: ‘We must halt the violence and bring an end to the humanitarian catastrophe now unfolding in Kosovo.’ 49 Implicitly this seems to be a claim to humanitarian intervention; it also claims to be an action to further the aims of the international community. That is, NATO seemed to be relying in part on a doctrine of implied authorization by the Security Council to justify the legality of its use of force.50 The official NATO statements left some uncertainty as to whether they were relying on an autonomous doctrine of humanitarian intervention or whether the Security Council resolutions and the doctrine of implied authorization had been a necessary part of the legal justification for the action initiated in March 1999.

In Security Council meetings a variety of arguments were put forward for and against the NATO air strikes. Those attacking the NATO action accused it of a clear violation of the UN Charter; they focused on the absolute prohibition of the use of force in Article 2(4), the primary role of the Security Council in the maintenance of international peace and security under Article 24 of the UN Charter, and the need for Security Council authorization under Chapter VII of the UN Charter rather than unilateral action. Some member states assumed NATO was a regional organization under Chapter VIII of the Charter and therefore limited also by the specific requirement in Article 53 that any enforcement action be authorized by the Security Council.51

The UN Secretary-General, speaking in response to the start of the NATO air strikes, reminded states of the primary responsibility of the Security Council for the maintenance of international peace and security; this was explicitly acknowledged in the NATO Treaty. Therefore the Council should be involved in any decision to resort to force.52

At the first emergency Security Council meeting called immediately after the start of the NATO air attacks, states supporting the action said it was taken as a last resort to prevent a humanitarian catastrophe after the failure of all diplomatic efforts to find a peaceful solution.53 Security Council resolutions had recognized that the situation in Kosovo was a threat to regional peace and security and invoked Chapter VII of the UN Charter. The USA took the line that NATO had acted to avert a humanitarian catastrophe and deter future aggression and repression in Kosovo. The UK offered a relatively extensive legal argument; it said, ‘The action being taken is legal. It is justified as an exceptional measure to prevent an overwhelming humanitarian catastrophe . . . Every means short of force has been tried. In these circumstances, and as an exceptional measure on grounds of overwhelming humanitarian necessity, military intervention is legally justifiable. The force now being used is directed exclusively to averting a humanitarian catastrophe, and is the minimum necessary for that purpose.’

At the subsequent Security Council meeting called two days later to vote on a resolution condemning the use of force by NATO the Security Council rejected the resolution by three votes in favour (China, Namibia and Russia) to twelve against.54 The draft resolution affirmed that the unilateral use of force by NATO constituted a violation of Article 2(4), Article 24 (on the primacy of the Security Council), and Article 53 (on the need for Security Council authorization of enforcement action by regional organizations). Those speaking against the NATO action (Cuba, India, Russia, China, Ukraine and Belarus) were clear that this was a gross violation of the Charter, whereas those defending the action concentrated on the continuing violence by the government of Yugoslavia against the people of Kosovo.

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