Since the initiation of the US-led airstrikes against Islamic State (or ISIL) forces in Iraq and Syria in August and September of last year, the legality of the strikes in Syria has been the subject of much discussion. Much of the focus has been on whether collective self‑defence – of Iraq – allows the use of force against non-State actors in foreign territory (Syria), where the territorial State (Syria) is ‘unable or unwilling’ to stop the attacks itself. However, the legality of airstrikes occurring on Iraqi territory does not appear to have occasioned any discussion at all (although see this previous post on the debate in the British House of Commons on authorising the use of force in Iraq). The presence of consent by the internationally recognised government of Iraq to the airstrikes (see here) seems to make legality of foreign military action against Islamic State under the jus ad bellum so obvious as not to require much commentary. However, a closer look at the scholarship on consent to the use of force reveals that the legality of what has variously been called ‘intervention by invitation’ or ‘military assistance on request’ has traditionally been more contentious than this simple statement would suggest. As discussed below, many scholars, and indeed some States, have suggested that there is a general prohibition on military assistance to governments in a situation of civil war or internal rebellion. This suggestion was particularly prominent in the Cold War era and seemed to represent an attempt to limit indirect uses of force by the superpowers. The rule is said to be derived from the prohibition of intervention in the internal affairs of other states, as well as from the principle of self-determination. The argument made by those in support of the rule is that intervention even with the consent of the government denies the people the right to govern their own affairs and to determine their political future. In short, on this view international law guarantees the right to rebel against the government. Others have doubted that a rule prohibiting assistance to governments in civil wars ever did emerge. This post seeks to demonstrate that recent state practice relating to the use of force in Iraq against Islamic State suggests that the evidence of opinio juris in relation to that rule is at present quite weak.
Support for a Rule Prohibiting Military Assistance to Governments in Civil Wars
According to a 1975 resolution of the Institut de Droit International on “The Principle of Non-Intervention in Civil Wars”, “[t]hird States shall refrain from giving assistance to parties to a civil war which is being fought in the territory of another State.” The resolution defines a “civil war” as a non-international armed conflict: a) between the established government of a State and one or more insurgent movements whose aim is to overthrow the government or the political, economic or social order of the State, or to achieve secession or self-government for any part of the State, or b) between two or more groups contending for control of the State in the absence of an established government. The resolution does recognize exceptions allowing the provision of “purely humanitarian aid” and a potential right of “counter-intervention” where illegal intervention has already occurred in aid of the other side in the civil war.
The existence of a prohibition similar to that set out in the 1975 IDI resolution has been recognized by eminent legal scholars. In a significant piece which includes a careful compilation of practice, Louise Doswald-Beck, writing in 1985, stated that “there is, at least, a very substantial doubt whether a State may validly assist another government to suppress a rebellion”, at least in the form of the sending of troops (arms transfers, in contrast, may be legal). According to Christine Gray, “[i]f there is a civil war rather than mere internal unrest, it has come to be accepted that there is a duty not to intervene, even at the request of the government, in the absence of UN or regional authorisation”, unless there has been prior foreign intervention against the government. Olivier Corten confines the permissible use of force with consent to “riposting to outside interference or protecting nationals, without extending to the settlement of internal strife.” In support of this view are Christakis and Bannelier, writing on this blog and elsewhere. Moreover, statements by States can be found to support a restrictive view of the legality of consensual use of force in civil war situations. A British Foreign Office policy document of 1984 (quoted in  BYIL 616) stated that “any form of interference or assistance is prohibited (except possibly of a humanitarian kind) when a civil war is taking place and control of the state’s territory is divided between warring parties”, although it also acknowledged an exception allowing “counter-intervention” in favour of one side of a conflict in response to previous outside intervention on the other side.
Opposition to a Rule Prohibiting Military Assistance to Governments in Civil Wars
However, the restrictive view of the legality of consensual force is far from universally accepted: scholars like Yoram Dinstein, Eliav Lieblich and Gregory H Fox argue that that any general prohibition on military assistance to governments faced by civil war is inconsistent with State practice. Writing relatively recently, Fox gives as an example the apparent acceptance by the international community of the legality of French military intervention in support of the beleaguered Malian government in 2013, despite – or perhaps because of – the fact that Islamist rebels controlled the north of the country and appeared to be on the verge of a drive towards the capital.
At the level of principle, the equation of situations of civil war with the exercise of the right to self-determination seems problematic. Though it is conceivable that “a people” might take up arms as a means of asserting that right, it cannot be said that just because there is an armed group that has sufficient military means to engage in what has become a civil war, this means that right to self-determination is engaged. As Lieblich argues, this “condones the view that the fulfilment of self-determination is a corollary of a party’s capability to effectively use violence.” The ability of an armed group to conduct a civil war does not necessarily indicate that they have a claim to represent “a people” within the meaning accorded to that term under the principle of self-determination. Likewise, in international law, one of the prerogatives accorded to the government is the ability to sanction activity within the territory of a state. It is not clear how military assistance with consent is not a violation of the prohibition of intervention in the internal affairs of a state when the “civil war” threshold is not crossed (even ignoring the difficulties of saying what that threshold actually is), but then becomes a violation of this principle once there is a civil war.
Continued divisions on the subject were apparent when the Institut de Droit International revisited the issue between 2009 and 2011. In his report as rapporteur, Gerhard Hafner raised the possibility that the 1975 resolution did not reflect state practice in the changed political environment of the post-Cold War world, although several members of the IDI disagreed. The IDI resolution adopted in 2011 on the topic of “Military assistance on request”, while “recalling” the 1975 resolution, did not explicitly reiterate its prohibition on military assistance to governments faced with civil war. However, it did state that “[m]ilitary assistance is prohibited when it is exercised in violation of the Charter of the United Nations, of the principles of non-intervention, of equal rights and self-determination of peoples and generally accepted standards of human rights and in particular when its object is to support an established government against its own population.” The 2011 resolution further specified that it was only intended to apply “to situations of internal disturbances and tensions… below the threshold of international armed conflict as defined in Article 1 of Protocol II Additional to the Geneva Conventions…” This leaves open the possibility that the prohibition on intervention expressed in the 1975 resolution was still envisaged as applying to non‑international armed conflicts within the definition in Additional Protocol II – that is, those between the government of a State and organized armed groups which exercise such control over part of a State’s territory as to enable them to carry out sustained and concerted military operations.
Legal Justifications for Action Against Islamic State in Iraq
The conflict between the Iraqi Government and Islamic State seems to fall within the scope of the prohibition put forward in the 1975 IDI resolution. At the time the airstrikes commenced Islamic State exercised control over a significant proportion of Iraqi territory, allowing it enable it to carry out sustained and concerted military operations, and it continues to do so. So if the prohibition on assistance to governments in civil wars only applies to conflicts falling within the definition in Article 1 of Additional Protocol II, that condition would appear to be met in this case. The current conflict seems therefore to provide a useful test case as to whether the prohibition put forward in the IDI resolution is actually part of current international law.
It is therefore significant that States participating in the airstrikes, in legally justifying their actions, have largely relied on a general assertion that military action on a State’s territory with the consent of its government is legal, without any reference to a prohibition of military assistance to governments facing civil wars. A senior United States administration official in a background briefing given on 8 August 2014 (the day the US operations began) stated that:
“ . . . with respect to international law, we believe that any actions we would take, to include airstrikes, would be consistent with international law, as we have a request from the Government of Iraq. So we’ve essentially been asked and invited to take these actions by the Government of Iraq, and that provides the international legal basis.”
President Obama’s notifications to Congress have emphasised that military actions in Iraq “are being undertaken in coordination with and at the request of the Government of Iraq…”.
Likewise, the UK government, in the summary of its legal position published on 25 September 2014, stated that:
“International law is clear that the use of force in international relations is prohibited, subject to limited exceptions. However, international law is equally clear that this prohibition does not apply to the use of military force by one State on the territory of another if the territorial State so requests or consents. It is clear in this case that Iraq has consented to the use of military force to defend itself against ISIL in Iraq.”
It is notable that this summary contained no reference to any prohibition on military assistance to a government in a civil war, despite the UK’s previous endorsement of such a restriction in the 1984 Foreign Office document referred to above. Similarly, the motion passed by the House of Commons to authorize the UK’s participation in the airstrikes on Iraq referred to “the request of the Government of Iraq for international support to defend itself against the threat ISIL poses to Iraq and its citizens, and the clear legal basis this provides for action in Iraq.”
Equally broad assertions as to the legality of the use of force with the consent of the territorial government were made by other participants in the coalition. The French Minister for Defence, speaking in the French Senate on 24 September 2014, justified the legality of French action by stating (my translation): “We act…in conformity with the Charter of the United Nations, for any State can in the exercise of its sovereignty request another State to provide it with assistance.” The Canadian Foreign Minister, explaining to Parliament the legal justification for Canadian participation in the airstrikes on Islamic State targets in Iraq on 6 October 2014, stated that “[t]he legal authorisation is that the democratically elected Government of Iraq has invited and asked for this support and assistance. The Security Council does not need to authorise it…” Similarly broad statements about the legality of the use of force with consent have been made by the Australian Prime Minister (who said in an interview on 16 September 2014 that “to operate in Iraq with the support, the consent, the approval, the welcome of the Iraqi government is perfectly, perfectly legal under international law”), and (it appears) by the Dutch government. The generality of these statements about the legality of the consensual use of force, combined with a lack of any reference to a prohibition on military assistance to governments involved in civil wars, seem to count against the existence of such a prohibition as part of contemporary international law.
Is Action Against Islamic State Simply an Application of an Exception to the Alleged Rule?
However, other interpretations are possible. It could be argued that the real reason that the airstrikes are legal, and that their legality has been accepted by most States, is not that there is no prohibition on military assistance to governments in civil wars, but that it falls within one of the asserted exceptions to this rule.
One exception apparently acknowledged in the 1975 IDI resolution and clearly accepted by scholars such as Doswald-Beck, Gray and Corten allows military assistance to the government where the opposition forces in the civil war are themselves receiving external assistance. It could be argued that the intervention against Islamic State falls within this framework, since Islamic State is not a solely Iraqi movement but also controls territory in Syria and recruits fighters internationally. Iraq has referred to the existence of an Islamic State “safe haven” in Syria as a factor necessitating its request for assistance. Further, in justifying their participation in the airstrikes, foreign leaders have unsurprisingly emphasised that Islamic State threatens not only Iraq but, because of its commitment to terrorism, their own nations. This framing of Islamic State as not simply an internal threat, but a regional and international one, may be interpreted as an attempt to bring the conflict out of the category of a civil war or a purely internal conflict – and thus as an implied recognition of, or at least as not in contradiction to, a general rule that military assistance to governments in such purely internal struggles is prohibited. Considering that Islamic State’s professed aims are not limited to taking over as the government of Iraq, but extend to the establishment of a caliphate which will “break…borders” all over the Middle East, the categorisation of the conflict as something other than a purely internal “civil war” seems plausible.
It has also been suggested by Christakis and Bannelier (also here and in this article in 2004) that, as an exception to the rule which they argue prohibits military assistance to governments in civil wars, military assistance to a government is lawful “when a State assists another during a joint fight against terrorism.” If such an exception does exist then the use of force against Islamic State would fall within it. However, as they themselves admit, “the problem which arises immediately is who can make the decision that a specific group is a terrorist group. Indeed established governments often try to portray their opponents as “terrorists” in order to de-legitimate them politically and be legally able to request external help against them.”
One problem with trying to carve out these exceptions to the supposed rule is that the circumstances indicated by those “exceptions” (and the supporting practice referred to by those scholars who support the supposed rule) seems to refer more to the motivations or reasons for which states provide military assistance to other states, as opposed to the legal justification for intervention. Whenever states take action they will undoubtedly have a policy reason for embarking on such action and will often, particularly in the case of action so serious as the use of force, set out that reason. However, it would be wrong to think that the motivation or reason equates to the legal justification as that would misunderstand the opinio juris element of custom.
While those states intervening in Iraq against Islamic State refer to it as a terrorist group posing an international threat and perpetrating atrocities against civilians, these states have in their specifically legal justifications for the use of force generally focussed in broad and unqualified terms on the legality of the use of force with the consent of the territorial State’s government. Therefore, States’ positions on the airstrikes on Islamic State in Iraq do not seem to support the existence of a general prohibition on the use of force at the request of the government in civil wars or internal conflicts.
However, it is also true that there is a trend, as observed by Fox among others, to justify military assistance to governments in terms of the (perceived) legitimacy of the government vis-à-vis its opponents – for example, whether it is democratically elected, or whether it is attempting to fulfil its responsibility to protect its population from atrocities. Although in general, States appear to have kept such legitimacy factors separate from their strictly legal justification of the use of force against Islamic State, there are some instances where these factors are apparently incorporated into the legal argument – for example, the Canadian Foreign Minister’s statement, quoted above, that the request from “the democratically elected government of Iraq” legally justifies Canada’s involvement in the airstrikes. A similar kind of shift may be indicated by the 2011 IDI resolution quoted above, which appears to replace a general prohibition on intervention in civil wars with a more specific prohibition against military assistance “when its object is to support an established government against its own population”. This may potentially make an assessment of the government’s (and the opposition’s) popular support and legitimacy the key factor. Whether these more value‑laden, ‘qualitative’ factors will evolve into an established and coherent rule limiting the general legality of intervention by invitation remains to be seen.