The fight against terrorism and SC Resolution 2249 (2015): towards a more Hobbesian or a more Kantian International Society?

Abstract

Security Council Resolution 2249 of 20 November 2015 was intended to open a new chapter in the fight against terrorism in general and against ISIS in particular. However, in academia this Resolution was received with criticism. After an analysis of SC Resolution 2249, it will be argued that the criteria developed for assessing jus ad bellum in inter-state relations are of no easy application in the relationship between states and non-state actors and in particular in regard to terrorists. If the prohibition of the use of force applies at all, this has to happen in a largely modified way. Fears that a lowered threshold for the use of force against terrorists will introduce a new “Hobbesian” element in international law do not appear to be justified. On the contrary, an international community showing more solidarity in the fight against terrorism will reinforce their Kantian traits. Resolution 2249 can offer an important contribution for such a development to take place.

1 Introduction

There are few United Nations Security Council (UNSC) Resolutions that received so much public attention as did the Resolution 2249 of 20 November 2015 on the fight against the Islamic State.¹ At the political level this Resolution became the focal point for a series of initiatives to “redouble and coordinate”² the efforts to fight ISIS. At the academic level, however, immediately after this document was issued, an intense debate concerning a series of pivotal concepts of international law set in.³ This short but fierce controversy has immediately revealed that the struggle against terrorism has all the ingredients to put into doubt convictions on issues of international law that seemed to be widely uncontested not far ago. In other cases ongoing legal developments have been accelerated.

While UNSC Resolution 2249 was considered by many lawyers as vague it is argued here that this Resolution can be seen as an important clarifying instrument not only with regard to the limits of forceful action against terrorism. It will be argued that the criteria for the use of force developed for the interstate context only partly apply to the field of international anti-terrorism law. As for the rest, far-reaching adaptions are needed. More fundamentally, UNSC Resolution 2499 raises the question as to where international law is headed. Are we regressing to a Hobbesian international legal order under the pressure of ever more violent terrorist attacks that compel us to take recourse to force? Not long ago a Kantian age of international peace seemed to be at arm’s length. In this paper, it will be argued that UNSC Resolution 2249, notwithstanding the licence to take recourse to force it furnishes, represents no reversal towards a Hobbesian order. There can be no doubt that terrorism and terrorist threats are an enormous challenge for modern international society. Nevertheless, if engaged in proper ways, this challenge can offer the international legal community the opportunity to become even more resilient and peaceful.

2 Framing the issue: SC Resolution 2249

In the immediate aftermath of its adoption, UNSC Resolution 2249 has been presented in two different ways: some portrayed it as an awkward example of a political compromise, an exercise in “constructive ambiguity”⁴ legitimizing the options taken by major stakeholders involved in the Syrian conflict. For others, this Resolution has to be read in a self-defence perspective even though this document does not explicitly mention this concept. According to this latter position, UNSC Resolution 2249 gives authoritative clarification as to the factual and legal situation ISIL terrorism has created.⁵ The situation resulting from these attacks would give life to a right to individual and collective self-defence according to Article 51 of the UN Charter.

It is contended here that the propositions mentioned above, while making some good points, do not do full justice to this Resolution. UNSC Resolution 2249 has to be read in a broader perspective, both with regard to the Security Council’s attitude towards the use of force in general as with regard to the United Nations’ fight against terrorism. It is argued here that UNSC Resolution 2249 is but a logical step in the Security Council’s history of law interpretation and law-making in this area.⁶ Far from obfuscating the legal situation, this Resolution lends more clarity to processes initiated long before. UNSC Resolution 2249 is part of a long array of Security Council Resolutions dealing with terrorism⁷ and here it stands out for the contribution it makes to further clarify the attitude of international law as to this phenomenon.

A look at the features of UNSC Resolution 2249 offers the following salient elements. First of all, among all terrorist groups constituting a major challenge on a regional or a global scale, ISIS is singled out as a ‘global and unprecedented threat to international peace and security,’ a qualification so far no terrorist group has ever been awarded. The Al-Nusrah Front (ANF) and all other individuals, groups, undertakings and entities associated with Al-Qaida are also considered to constitute a threat to international peace and security but UNSC Resolution 2249 clearly pinpoints ISIS as the major challenge. Being a “global and unprecedented” threat to international peace and security ISIS requires primary attention.⁸

The UN Security Council gives an assessment of the threat resulting from ISIS and dares a projection of its future development. This outlook is scary when the Security Council in paragraph 1 of the Resolution’s operative part notes that ISIS ‘has the capability and intention to carry out further attacks’. It refers to ‘all such acts of terrorism as a threat to peace and security.’ In what follows, this paper will examine whether this outlook undertaken by an authoritative institution has also legal implications.

Probably the most important provision is to be found in paragraph 5 in which all Member States that have the capacity to do so are called upon to take all necessary measures ‘to redouble and coordinate their efforts to prevent and suppress terrorist acts committed by ISIS’ as well as Al Qaeda and other terrorist groups designated or to be designated by the UN. Paragraph 5 is, however, as a whole not an easy read and pivotal provisions are strongly qualified.

First of all, only those Member States are called upon to take all necessary measures that “have the capacity to do so”. A lack of capacity may relate primarily to the material (military or financial) level but it may also be of a legal or political nature⁹. At a first sight, this qualification is very broad and might provide a facile excuse for non-participation. In reality, however, a strict reading of this qualification might be more appropriate to intent and structure of this Resolution. In fact, Resolution 2249 leaves no doubt as to the extraordinary challenge ISIS terror poses and therefore no easy escape clause can be provided in face of such a threat. It is rather to be assumed that this qualification allows to “graduate” the various contributions. While there may be countries unable to provide any assistance in this fight the vast part of countries will be able to give at least some contribution. In sum, this qualification only emphasizes the aspect of solidarity: Assistance has to be given but in this due consideration can be paid to the actual possibilities of the single Member State.

The efforts to prevent and suppress terrorist acts committed by ISIS and other terrorist groups have to be “redoubled and coordinated”, but only “on the territory under control of ISIL in Syria and in Iraq”. Therefore, this Resolution does not envisage measures for the whole territory of Syria or Iraq and even less measures that should take place outside these states. As is well-known, in the meantime ISIS has bases in several countries. Before Syria, it was in Iraq, its first breeding nest, and afterwards it sprang to several other countries, in particular to Libya, a “failed state” where it build up a larger stronghold. Resolution 2249 does not deal with these situations and even less does it provide a basis for regime change in Syria.

Finally the question has to be addressed which measures the SC had in mind when drafting para. 5 of Resolution 2249. Efforts to “prevent and suppress” terrorist acts may call to mind “sting operations” and singular preventive measures to counter terrorist acts not really dissimilar to those executed also in other countries with stronger ISIS and Al Qaeda presence such as Yemen. The wording used in the last clause of para. 5 “and to eradicate the safe haven they have established over significant parts of Iraq and Syria” hints, however, at stronger measures implying the use of a larger scale of force. We are here no longer in the realm of “police action” but it comes clear that such operations have to be of a genuine military nature.

3 Does Resolution 2249 open the way for the use of force under Chapter VII of the UN Charter?

The foremost question Resolution 2249 raises is whether this document opens the way for the use of force under Chapter VII of the UN Charter. On this subject, Resolution 2249 lacks in final determination. However, a look at Security Council deliberations since the founding of the UN reveals that this attitude is not new but common practice. UNSC Resolution 2249 fits very well in the long series of Security Council resolutions on Chapter VII, the most important exception to the prohibition of the use of force. Resolution 2249 may therefore be innovative partly in its wording and in its overall structure, yet it is very traditional in its vagueness.

As is well-known, the procedure envisaged by Chapter VII for the activation of the peace enforcement system has never come to life as Member States were not prepared to make available armed troops to the Security Council on the basis of specific agreements as set forth in Article 43 of the UN Charter .¹⁰ The “principal” (or centralized) model, whereby the UN should directly enforce peace by its own troops should be replaced by the “agent” (or decentralized) model according to which the UNSC should only provide an “authorization” for the use of force carried out by Member States.

Originally this model was heavily criticized as a violation of the UN Charter,¹¹ but today it seems to have acquired a customary law status due to its wide acceptance.¹² This fact reveals that the provisions of the Charter are not to be seen rigidly, but suited for further development according to the needs in practice. The qualification coined for the European Convention of Human Rights as a “living instrument”¹³ can therefore be transposed also to the UN Charter. This seems all the more true if we consider that the respective provisions pertain to the cornerstone of the whole UN law,¹⁴ the prohibition of the use of force and its exceptions, and are therefore particularly delicate.

The delicacy of this question finds expression, first of all, in the need to circumscribe the delegated powers. Unfortunately, both the difficulties met in the consensus finding process within the UNSC as well as the impossibility to anticipate all possible developments on the ground and the ensuing need to adapt action, to a certain extent, to the factual situation encountered, require a certain amount of flexibility when implementing the authorization. This flexibility, of course, ought to have its limits and according to widespread opinion, often voiced in literature, these limits have been violated on the occasion of the enforcement of the no-fly-zones in Iraq. When UNSC Resolution 1973 of 2011 on the implementation of a no-fly-zone in Libya became de facto the basis for implementing regime change, nowhere allowed by this Resolution, the need to limit flexibility became even clearer.¹⁵ It was in particular this latter Resolution that evidenced how the UNSC loses control over enforcement once this power is delegated according to the decentralization model.¹⁶ The UNSC’s appalling lethargy in the Syrian case can be attributed to a considerable extent to the shortcomings of the enforcement process in the Libyan case.

Assuming however that the problem of the extent and the limits of the delegation can be handled, the prior problem of just what elements the “authorization” model presupposes remains. Unfortunately, the UNSC practice is less than clear on this issue. According to a strict, orthodox approach, the following elements have to be given for a Security Council authorization to be fully in conformity with the Charter:

• a determination in accordance with Article 39 relating to the existence of any threat to the peace, breach of the peace or act of aggression;

• the chapeau “acting under Chapter VII” and

• an operative paragraph containing a “decision” to authorise Member States to use force.¹⁷

There can be no doubt, however, that a strict reading of these requirements would not do justice to the complexities of decision taking and law-making within UNSC. It is rather the case that the overall context has to be given primary attention,¹⁸ balancing this subjective criterion with the requirement of appropriate formal substance so as to give due respect to bona fides relying heavily on form and transparency. First of all, it can hardly be argued that the authorization regime should presently be the only key to use force according to Chapter VII of the Charter. It is true that the UNSC has not given any explicit authorization to use force in this case; the verb “to authorize” is not used in this document. Nonetheless, in the decisive paragraph 5 of UNSC Resolution 2249 Member States are “called upon” (to take all necessary measures) and it can be argued that thereby an even broader gate for the use of force is opened. In fact, by an “authorization” the principal (the Security Council) permits the agents (Member States) to act. Here, these are the Member States who require the permission to act. If a “call” is issued it is the principal who becomes active in the first place requiring the agents to act subsequently.

This is not a somewhat reluctantly given permission to act; in fact the Member States are summoned to do so. “To call upon” is more of an imperative act than a permissive one. Behind the “call” there is far more impetus than behind an “authorization.” It could be argued that here the use of force is not permitted but required. Of course, reference to the general use of language cannot give an exhaustive answer for the interpretation of UN norms and acts.¹⁹ Of primary importance is rather the meaning resulting from the UN practice itself, the way UNSC understands this term in dialogue with the Member State. The relevant practice of the UNSC has therefore to be taken into consideration in order to see how this concept has been employed. Such an enquiry reveals that “calls” have in fact been issued to prompt States to intervene with armed force.²⁰ “To call upon” is not much dissimilar from “to require” and in fact also this latter term has been used while adopting binding Chapter VII resolutions even without making any explicit reference to this Chapter.²¹

The resolution that perhaps comes closest in this approach to UNSC Resolution 2249 is Resolution 221 of 9 April 1966 by which the UN Security Council tried to make effective an earlier embargo against Southern Rhodesia governed by the illegitimate white apartheid regime under Ian Smith. At issue was an enforcement of an oil embargo. A private oil company wanted to bypass the embargo that the United Kingdom, possibly in collaboration with Portugal, wanted to stop. In this situation Portugal, the colonial power responsible for the territory of Mozambique from where the oil could be pumped to Southern Rhodesia, was called upon not to receive oil destined for Southern Rhodesia at the port of Beira (Mozambique) while a further call was directed to the United Kingdom attributing respective enforcement powers to this state. This Resolution therefore created both negative obligations (obligation to desist) and positive obligations (obligation to act) as it also mentioned explicitly the subjects of these obligations. This specific reference to single addressees of the various obligations contained in Resolution 221 makes clear, however, that the similarities with UNSC Resolution 2249 must not be overemphasized. In fact, no such specific reference can be found in this latter resolution which addresses the Member States in their entirety with the sole limitation referring to “capacity.”

Alongside UNSC Resolution 221 of 1966, UNSC Resolution 83 of 27 June 1950 could be mentioned as a predecessor model for UNSC Resolution 2249. UNSC Resolution 83 was the first ever considered to implement the authorization model. It was issued after the attack by North Korea against South Korea and it recommended that Member States provide assistance to the Republic of Korea ‘as may be necessary to repel the armed attack and restore international peace and security in the area.’ In this case the addressees of the resolution are all the Member States.

Nonetheless, notable differences with regard to Resolution 2249 remain. In fact, notwithstanding the open formulation there was little doubt which states were considered for a military intervention in Korea. With regard to UNSC Resolution 2249 this is by far not so evident. Indeed, while UNSC Resolution 83/1950 was more or less clear as to which states had to participate in the intervention, UNSC Resolution 2249 is not as clear.

Thus, at this point, it is not fully evident whether the formula “calls upon” in UNSC Resolution 2249 legitimizes the use of force according to Chapter VII of the Charter in a way similar to the “authorization” model; no directly corresponding UN practice can be discerned. The UNSC has confirmed the existence of a qualified (“global and unprecedented”) “threat to the peace” (a direct reference to Article 39 of the Charter) and called upon Member States, at least those capable to do so, to “take all necessary measures,” thereby implicitly referring to Article 42 of the Charter. So, Chapter VII is touched upon twice without being mentioned explicitly. There can be no doubt that these ambiguities and complexities pertain directly to the enemy that here comes into play, which, despite its name, is not a state but a terrorist group. Should this lead to a totally different reading of Resolution 2249, a reading in terms of self-defence and therefore in line with UNSC Resolution 1368 (2001)? Some have suggested so.²² This calls for a closer examination of the relationship between the right to self-defence and the fight against terrorism in international law.

4 UNSC Resolution 2249 and the right to self-defence

At first sight it appears to be difficult to read UNSC Resolution 2249 as allowing for or facilitating in any a way the exercise of a right to self-defence. Nowhere in this document reference is made to this concept, not even implicitly. It has been suggested that the reference in paragraph 1 of UNSC Resolution 2249 to ‘the capability and intention [of ISIS] to carry out further attacks’ should be read as an authoritative confirmation of the “immediacy” element required to permit a response in terms of self-defence.²³ As will be seen later on, this view does not withstand closer scrutiny.

In the past, before 11 September 2001 the fight against terrorism was primarily seen as a question of national law enforcement,²⁴ even though trans-border actions did occur. Terrorists were treated as pure criminals; the international element in this fight was more or less confined to transnational police cooperation. ²⁵ As to international measures in the stricter sense, state attitude depended on the specific circumstances. In the face of attacks by terrorist groups with international connections, the reactions regularly bore some international elements but there were no consistent and coherent traits. The bombing of Pan Am flight 103 over Lockerbie in 1988 that killed 270 people did not lead to military measures but rather to prosecution in the Netherlands under British law,²⁶ although initially forceful measures were considered as an option. In some situations, however, armed responses followed. This was the case in 1986 when Libyan agents bombed a Berlin discothèque provoking American air strikes in Bengasi and Tripoli. The same holds true also for the attacks on the US embassies in Nairobi and Dar es Salam in August 1998 that killed and wounded hundreds of people. Here, the US responded by missile attacks on alleged terrorist camps in Afghanistan and on a pharmaceutical plant in Khartoum that served as a bomb factory according to US intelligence source. Israel and Turkey had for many years advanced the self-defence argument for their military operations against Palestinian and Kurd fighters.²⁷ Overall, these justifications met, however, with strong opposition by the international community or, at best, they were ignored. The self-defence argument was therefore far from being generally accepted.²⁸

The attacks on the Twin towers of 2001 changed all this. At least this was the first impression that came to mind when the UNSC adopted Resolution 1368 a day after the attack, on 12 September 2001. In its preambular part, this resolution refers indirectly to Chapter VII when it voices its determination ‘to combat by all means threats to international peace and security’ and expressly to the inherent right of individual and collective self-defence in accordance with the Charter, and therefore to Article 51 of the Charter without mentioning this provision. A similar position was echoed in Resolution 1373 of 28 September 2001.²⁹ Equivocal as these statements were, they were afterwards read as the first official pronouncement by the UNSC Security Council as to the application of the right to self-defence also against terrorist groups.³⁰ When asked how these statements should fit into the existing international legal order and what this should mean on the practical level, legal interpreters seemed puzzled. There was a strong opinion in literature that the statements in Resolution 1368 and 1373 of 2001 were of an outspoken emotional character due to the nature and the impact of the attacks of 9/11 and that no new legal ground had been broken.³¹ And in fact, for more than a decade, the UN Security Council did not take up again this approach with regard to other situations of terrorist attacks. The question whether self-defence was allowed with regard to terrorist attacks had therefore to be answered on the basis of general international law, and, in particular, with reference to inter-state relations. This proved to be a daunting task.

As a matter of fact, Article 51 of the UN Charter applies also to terrorist attacks.³² But for a long time this provision has been primarily read under the perspective of state responsibility, an approach that led in several cases to awkward, not to say aberrant solutions. The leading—and often also misleading—case is the Nicaragua case decided by the International Court of Justice (ICJ) in 1986. There the ICJ stated the following:

[T]the prohibition of armed attacks may apply to the sending by a State of armed bands to the territory of another State, if such an operation, because of its scale and effects, would have been classified as an armed attack rather than as a mere frontier incident had it been carried out by regular armed forces.³³

The ICJ is adopting here a traditional, conservative logic. First of all, the acts by “armed bands” must be attributable to another State (and in this regard a very high and therefore much criticized threshold is applied). Secondly, a considerable intensity is required for such an attack to qualify as an armed attack. In other words, for Article 51 to apply in the face of such activities the dimension of the military measures must be the same as in the case of an attack by a State and behind these activities there must again be a state.³⁴

This pronouncement left important questions unaddressed, thereby creating the misleading impression that all these situations would automatically be excluded from the purview of Article 51. Unfortunately, in two subsequent cases the ICJ missed the opportunity to clarify this issue. In the Wall Opinion of 2004 the ICJ would have had the unique chance to bring clarity to this subject as the self-defence argument with regard to non-state actors was explicitly advanced by Israel. In a highly convoluted and sketchy paragraph, the ICJ, however, came to the conclusion that Israel could not justify the building of the wall by invoking Article 51 as Israel had not been able to impute the attacks to a foreign state or to an external threat to which UNSC Resolutions 1368 and 1373 referred.³⁵

As it appears, this case was so highly contentious and politically charged that the ICJ sought a way out that proved to be technically a really fortunate one. Again, however, the false impression was created that Article 51 applied only to inter-state relations.³⁶ One year later, the ICJ again dodged this question by giving on the one hand the impression that it still stuck to a strict reading of the Nicaragua pronouncement while on the other hand admitting that it left open the question whether self-defence was allowed against ‘large-scale attacks by irregular forces.’³⁷ One door was closed and the other opened and the interpretation of Article 51 was left where it stood before.³⁸

Needless to say that the fundamental problem in this regard lies in the fact that terrorists do not reside in sovereignty-free areas. As soon as they operate internationally, at least one further sovereign state order is—at least implicitly—involved. If terrorists act as agents of this other order, the Nicaragua formula can apply without problem but the real difficulties arise as soon as such a relationship cannot be proved. State practice has developed the concept of the “harbouring state,” a state giving shelter to terrorists and therefore engaging in some sort of complicity.³⁹ This may be something less than “sending armed groups” but nonetheless these states engage responsibility. Armed response to terrorist attacks may be justified if all other criteria, in particular proportionality, is adhered to. In this context, reference has also been made to the idea of “aiding and abetting,” a criterion borrowed from international criminal law.⁴⁰ It can be noticed that these approaches, although remaining within the realm of state responsibility as devised by the ICJ in the Nicaragua case, considerably soften the criteria for attribution. With terrorist attacks gaining ever more destructive power state interests have to be rebalanced taking into due account also the interests of individuals.

In some senses, this rebalancing is conducive to a sliding slope. The standard for attribution immediately below that of “aiding and abetting” is that of the state “unwilling or unable” to fight terrorists effectively permitting thereby these groups, directly or indirectly, to use the respective state territory as a basis for international terrorist attacks. Here the state, out of whose territory the terrorists operate, is no longer a “harbouring” state but simply a “host state.” Should self-defence be permissible also in this case? An answer pointing forcefully in the positive was given to this question by the Legal Advisor to the State Department under the Bush Administration:

[A] state must prevent terrorists from using its territory as a base for launching attacks. As a legal matter, where a state is unwilling or unable to do so, it may be lawful for the targeted state to use military force in self-defence to address that threat.⁴¹

Here we are one step in (“unwilling”) and one step out (“unable”) of the attribution approach. A military response should therefore be possible even if the attitude of the country from which the terrorist attacks are launched is irreproachable. In literature, doubts were expressed, however, whether the “unwilling or unable”-criterion, so forcefully advocated by the United States after 9/11, already constituted customary international law. In fact, when Russia attacked Chechen rebel forces in Georgia declaring that the host state was “unwilling or unable” to prevent terrorist activities going out from her territory, the US staunchly opposed this justification.⁴²

Now we have to ask at what stage this legal development is at present. The inconsistency of the claims and statements referred to above does not, as such, prove much as in such a delicate area political considerations will always interfere with neutral long-term considerations. Some authoritative research and policy papers issued between 2005 and 2012, the Chatham House Principles⁴³, the Leiden Policy Recommendations⁴⁴ and the Principles on ‘Self Defence against an Imminent or Actual Armed Attack by the Non-State Actors’ (the so-called “Bethlehem Principles”)⁴⁵, suggest that we are already at a point where a fully-fledged right to self-defense against terrorist attacks exists.⁴⁶ Thus, for example, Chatham House principle no. 6 states that ‘the right to use force in self-defence is an inherent right and is not dependent upon any prior breach of international law by the State in the territory of which defensive force is used.’ The Leiden Policy Recommendations expressly side with the “unwilling or unable” approach⁴⁷ and this is also the case for the Betlehem principles.⁴⁸

These principles, though well-respected their authors may be, are not binding international legal rules. They nevertheless convey a sentiment that is gaining more and more hold within the academic community. For some international lawyers now a customary international law rule exists according to which self-defence is permissible also against non-state actors whose acts are not attributable to a state.⁴⁹ UNSC Resolution 2249 forcefully strengthens this view.

5 The specific characteristics of self-defence against terrorism

In default of specific provisions in the UN Charter on how to tackle threats like those stemming from modern international terrorism the criteria developed by the ICJ on permissible self-defence between states, by and large, have been extended also to the fight against terrorism. With some of these criteria already highly contested in the inter-state context their application to non-state actors should lead to aberrant conclusions in particular if no attribution to states was possible. This becomes evident already if we look at the time factor, the request that the threat of an attack should be immediate. As is well known, the time factor is of decisive importance for assessing the legality of self-defence measures.

The wording of Article 51 of the UN Charter seems to require that an attack has already occurred. Legal interpreters, often referring to the Webster-formula of the Caroline case,⁵⁰ argue that self-defence is legal if an armed attack is “imminent”. Anticipatory self-defence, against a threat that has not yet fully materialized, is recently considered to be inadmissible. In practice, these notions are, however, hard to distinguish. It is in particular not easy to state when the condition for “imminence” is met. It is therefore doubtful whether these considerations can find application in the context of the fight against terrorism, or, respectively, whether this criterion finds application in this context at all. It was said that UNSC Resolution 2249 created a situation of ‘permanent imminence of the threat’ and that ‘[i]n confirming that ISIL represent a permanent and active threat of further attack, the Council appears to relieve individual states from having to fulfil the criteria for self-defence when considering armed action in Syria.’⁵¹

This is surely an ingenious proposition but in the context of the fight against terrorism it is not really useful or convincing. In fact, the criterion of “immediacy” has been introduced in order to make sure that between states (unilateral) recourse to force is taken resort to only under absolute exceptional and strictly limited circumstances. In all other cases, impending attacks should be ward off by taking recourse to one of the many instruments the Charter offers in the field of peaceful settlement of disputes or by multilateral measures ordered (or authorized) by the Security Council. The far-reaching prohibition of the use of force applying between states is closely related with respect of sovereign equality. No such respect is due towards terrorists. They may wield power equal to that of a state but legally they are not at the same level and they should never become. There is no need to restrict self-defence to an “immediate” threat of an attack by terrorists as, with the exception of human rights or humanitarian law, no restriction or “peace clause” applies towards terrorists. Only if their acts can be attributed to a State again the general rules—requiring utmost respect for state sovereignty—apply.

Similar considerations apply with regard to the so-called gravity test. In literature, much confusion reigns also in this regard. While many analysts contend that an attack has to be large scale in order to generate a right to self-defence,⁵² such a requirement is commonly set for an attack by an armed band or terrorists. The motive for this is usually sought in the Nicaragua judgment, but erroneously, as has been demonstrated in literature.⁵³ In fact, there is no reason to require that acts of terrorists should be of higher gravity than that of states in order to qualify as aggression.⁵⁴ While it may be reasonable to pretend the same amount of gravity if terrorists act as agents of a state, the fight against terrorists with no such relationship to a state should not be made dependent upon such gravity of the acts committed. As demonstrated above, there is no need to show restraint of whatsoever kind against terrorists.⁵⁵ Prudence is needed only insofar as the sovereignty of the hosting state has to be respected. In this regard, however, respect of the proportionality criterion should be sufficient in order to make sure that state sovereignty is adequately respected. It has also been said that there was the risk that forceful measures against terrorism, due to their punitive and deterrent character they often evidence, could re-introduce the concept of armed reprisals the outlawing of which was such an important achievement in the development of international law.⁵⁶

Once again, there is the peril of confusing different levels of international law. While between states armed reprisals have to be strictly outlawed if the UN peace order based on the prohibition of the use of force is to be preserved, no such containment is called for in the struggle against terrorism. Terrorists, or, respectively, terrorist groups are not bearers of sovereign rights and even less they become part of a system of sovereign equality. To fight them does not endanger the peace order, quite the contrary. Often, when forceful countermeasures against terrorist acts are taken, rhetoric and timeframe, with action and counter-action often widely separated in time, may call to mind inter-state reprisals but legally the situation is a totally different one. While punitive measures against states are outlawed also because alternative dispute settlement procedures are available, this is not true for the fight against terrorists. In this sense, this struggle is also far more archaic and resembles that between states (or, even before the creation of states, between rivalling entities) in ancient times.

A last brief consideration has also to be given to the question whether the fragile nature of the Syrian state broadens the scope for any possible intervention. This question has to be answered in the negative. Syria has an internationally recognized government and even if government troops have withdrawn from many regions and are embattled in others state sovereignty is still in place and foreign intervention is prohibited without authorization by the government or the UN Security Council. In an argumentum de minore ad maius it should be remembered that the use of force is even prohibited against de facto regimes or failed states.⁵⁷

UNSC Resolution 2249 has set the course for the direction future interventions in Syria can take: they are geographically limited to a certain region, they have been confined to certain addressees and they must not infringe Syrian sovereignty. This last condition does not result explicitly from UNSC Resolution 2249, but reference to the need that measures be taken in compliance with international law, in particular with the UN Charter, has clearly to be read in this light.⁵⁸

6 Conclusions: moving from a Hobbesian perspective to a Kantian one

We can now bring the two strings developed in this paper together: UNSC Resolution 2249 is at the same time innovative and an expression of a longer term legal developments that started in 2001. This resolution gives comprehensive expression to Chapter VII, both with regard to the first articles of this Charter (Articles 39–42) as with regard to the last one (Article 51). The power to use force against terrorists is further developed, as it is the case with the right to self-defence.

UNSC Resolution 2249 is neither to be seen as a resolution of pure authorization nor primarily as a document specifying the criteria for self-defence in a specific case. This resolution lies somewhere in between and addresses Chapter VII as a whole. States fighting ISIS are defending themselves but also the international community as a whole and for this they are called upon to act. As shown, UN practice has evidenced considerable flexibility in the application of the Chapter VII provisions.⁵⁹ It can be argued that Resolution 2249 adds a new approach if the fight against terrorists such as ISIL is at issue.

At the same time, UNSC Resolution 2249 pays due regard to state sovereignty. Intervention is allowed only with regard to a circumscribed geographic area and in relation to clearly identified groups. On the basis of UNSC Resolution 2249 military intervention should be possible only on request or at least in cooperation with the Syrian government.⁶⁰ Cooperation and coordination is also required between the interveners. If the conflict in Syria is considered to be a civil war only an intervention on invitation (or at least toleration) by the legitimate government (whatever its democratic credentials may be) is permissible. The concept of negative neutrality proposed by some lawyers in the aftermath of WWII as guiding principle for civil war intervention surely no longer applies to situations where the fight against terrorists is at issue.⁶¹ There is no neutrality in the fight against terrorists.⁶² The paradox resulting from these developments is that, contrary to long held fears, state sovereignty is not weakened if stronger measures against terrorists are allowed. The need to respond to an extraordinary challenge as the fight against international terrorism, has brought about this remarkable result. A few years ago, fears were voiced that a more extensive transnational use of force in the fight against international terrorism would transform Grotian international society into a Hobbesian order, in which obsession for security would lead to the violation of pivotal international agreements on which our present international legal order rests.⁶³

UNSC Resolution 2249 seeks to demonstrate that such a development is not a necessary one. On the contrary, exactly such extraordinary challenges like international terrorism may be conducive to a more Kantian state order in which the international rules on the use of force are reformulated in order to allow for a more effective repression of such attacks according to commonly agreed rules and under the supervision of the UN. UNSC Resolution 2249 was intended both to fight international terrorism more effectively and to ensure that this happens unilaterally as unilateral action has proved to be neither effective nor conducive to a more stable international order. Contemporary international terrorism constitutes a threat that could not be anticipated in 1945 and consequently Chapter VII does not face this issue squarely. It has been shown that the flexibility the UN rules revealed already in the past⁶⁴ is still in place so that UN law may adapt them to this new task without any need to change the letter of the Charter.⁶⁵ As evidenced, the jus ad bellum rules developed on the basis of the UN Charter apply only partly to the fight against terrorists and for the rest they have to be adapted to a situation with largely different requisites.⁶⁶ This new interpretation of the Chapter VII rules will not lead to a more anarchical international society but rather to a society that effectively repels the threat of such an anarchy.