I have elsewhere explained why the UK acting against Da’esh target in Syria, at the request of the Iraqi government in the latter’s self defence is lawful. In acting against a non-state such as Da’esh the basis of such action is that the state from which they are attacking is ‘unable or unwilling’ to stop such attacks. Here I will seek to discuss some objections that might be made to this.
The UN Charter states
Article 51 Nothing in the present Charter shall impair the inherent right of individual or collective self-defence if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.
The first thing to note is that the right to self defence is not embodied in the UN Charter itself. Instead it states that nothing in the Charter shall impair the right of self defence (until the UNSC has taken the necessary steps to ensure peace). The defence is therefore recognised but not incorporated by article 51. Because it is not codified, the scope of self defence has to be determined by a combination of custom and ethical principle.
Does this right of self defence apply as against non-state actors? The answer to this question is emphatically (and perhaps surprisingly) no. The parties to international law are states: the right of self defence is one of three situations where it is lawful for one state to use force in another state’s territory (the others being a Security Council resolution under Chapter VII of the Charter, or with that other state’s consent). International law is much closer to a domestic law of contract than to a law of crime. The only parties to it are states, and their obligations are created by agreement which are either express or implied by custom.
Does that mean that any attack on Da’esh (which is not a state) is unlawful? Again, the answer is no. First, action within Iraq by the Iraqi government and those assisting it (such as the UK) is perfectly lawful because it is taking place within the territory of Iraq. Self defence is neither here nor there as Da’esh is not a state that could be wronged by military action taken against it within Iraq.
Second, action against Da’esh within Syria is potentially wrongful vis a vis the Syrian state (and not Da’esh). Self defence gives states a freedom to act vis a vis other states that they would not otherwise have. Da’esh (as a non-state) is invisible in the system of rights governing the relationship between states.
As Da’esh are not attacking Iraq under the direction or control of the Syrian government, does that mean that Iraq (and its allies) have no freedom to use force within Syria? This would indeed be a surprising conclusion as it would mean that a non-state terror organisation such as Da’esh could attack states with impunity in a way that states could not.
The recognised answer is that where one state is “unable or unwilling” to suppress attacks coming from its territory, the attacked state may use force in the other’s territory to suppress it.
One objection to Iraq (and its allies) acting against Da’esh in Syria might be that the consent of the Syrian government has not been obtained. Should the UK ask for such consent before using military force in Syria?
Politically, there are good reasons why no UK government would in practice do so. It seems probable that in 2013 Assad used sarin gas in opposition controlled areas of Damascus, and other atrocities. Asking Assad for permission is not going to happen.
The point of seeking such consent would be to show that the host state was unwilling to tackle the non-state actor from within its borders. A refusal to consent, coupled with a failure to act, would demonstrate collusion by the harbouring state.
However, the refusal of consent would not demonstrate (or be relevant to) the question of whether the host state was unable to tackle the non-state actor. Since 2013 it has been proven beyond peradventure that the Syrian state is unable to suppress Da’esh.
If consent were sought from the Syrian government there would be two possible outcomes. Either consent would be given (in which case action against Da’esh in Syria would be lawful) or it would be refused (in which case action against Da’esh would be lawful on the basis that Syria was unwilling to take the steps necessary to suppress Da’esh). Such a formal step is not required as it is objectively demonstrable that Syria is unable to prevent attacks from its territory.
The United Kingdom has not been attacked by Da’esh, does that mean that we cannot act? The answer is, of course, no. If Belgium is attacked it is not just the state of Belgium that may act in its defence, but also those other states it authorises to act on its behalf. What is true of Belgium (or France) is true of Iraq. Collective self defence is expressly relied upon by the UK as grounding the legality of acting in Syria.
By resolution 2249 the UNSC called upon
Member States that have the capacity to do so to take all necessary measures, in compliance with international law, in particular with the United Nations Charter, as well as international human rights, refugee and humanitarian law, on the territory under the control of ISIL also known as Da’esh, in Syria and Iraq.
This was not a resolution under Chapter VII, and so does not itself give a mandate for military intervention in Syria by Member States. However, the phrase ‘all necessary measure’ encompasses military force. Implicitly the resolution endorses the proposition that it is compatible with international law for Member States to take these steps. If it were not so, the UNSC would be calling on Member States to behave unlawfully.
That acting against Da’esh in Syria is lawful does not, for good or ill, answer the ethical question of whether it is right to do so. That is a hard question that I shall seek to return to. What can be said however is that those who would claim that it is unlawful, or that yet further resolutions of the UNSC are required are trying to avoid giving an answer to that much more difficult question.