An International Law Assessment of the Collective Self-defence Clause of the 2021 Treaty on the ‘Establishment of Strategic Partnership of Cooperation in Matters of Defence and Security’ between Greece and France

On 28 September 2021 France and Greece concluded a bilateral treaty on the ‘Establishment of Strategic Partnership of Cooperation in Matters of Defence and Security’ (see the Greek and French version here. The Treaty has not been translated yet into English). The Treaty is premised on a community of interests in matters of foreign policy, defence, and security between France and Greece, which is materialized through consultation, cooperation, and assistance.

In this post, we will consider, first, whether the collective self-defence clause in Article 2 of the Treaty is compatible with Article 51 of the UN Charter and the customary law of self-defence and, secondly, whether it is compatible with the North Atlantic Treaty (NAT) since both parties to the Treaty – France and Greece – are members of the UN and NATO.

According to Article 2 of the Treaty, the parties shall provide to each other aid and assistance, with all appropriate means at their disposal, and, if necessary, with the use of armed force, if they jointly determine that an armed aggression occurs against the territory of one of the parties, in accordance with Article 51 of the UN Charter (authors’ translation of the Greek and French text which provided: ‘Les Parties se portent mutuellement aide et assistance, par tous les moyens appropriés en leur possession, si besoin l’ emploi de la force armée, si elles constatent conjointement qu’ une agression armée survient contre le territoire de l’ une d’ entre elles, conformément à l’ article 51 de la Charte des Nations unies’).  

Article 2 falls squarely within the ambit of Article 51 of the UN Charter but whereas Article 51 establishes a permissive right to collective self-defence with no corresponding duty, Article 2 of the Treaty contractualises, bilaterises, and concretises collective self-defence by creating mutual legal commitments.

Such an obligation is however subject to a number of prerequisites that reflect those recognized in Article 51 and customary international law as affirmed by the ICJ in its 1986 Nicaragua v. USA judgment. They are: (a) the occurrence of an ‘armed attack’; (b) a declaration by the victim-State that is indeed the victim of an armed attack; and (c) a request for assistance by the victim-State (see here paras 195, 199, 211).

In the same vein, collective self-defence action according to Article 2 is conditional on the existence of an armed attack and on the parties’ agreement that an armed attack is taking place. This is due to the fact that collective self-defence as the ICJ repeatedly opined cannot be exercised on the basis of one state’s own assessment of the situation (see Nicaragua v. USA here para 195), lest it amounts to unlawful intervention. Moreover, since Article 2 creates mutual rights and duties, the parties should agree on the circumstances that give rise to a right to be defended and the corresponding duty to defend in order to be able to perform them. Such determinations are done on an ad hoc basis but this is not at all peculiar in the absence of a settled definition of ‘armed attack’. If no agreement is reached, the collective self-defence clause of the Treaty is not triggered but the fall-back provision is Article 51 of the UN Charter.

That having been said, a number of questions about the scope of Article 2 remain open.

First, Article 2 employs the term ‘armed aggression’ whereas Article 51 of the UN Charter and customary international law require an ‘armed attack’. Article 2 does not however expand the scope of collective self-defence due to its express reference to Article 51 of the UN Charter. That having been said, an ‘armed attack’ is not defined in the Treaty and there is no settled definition in international law. In its 1986 Nicaragua v. USA judgment, the ICJ ruled that an armed attack is a use of force of a ‘scale and effects’ that exceeds that of a frontier incident (see here, para 194-195); however, the same court also ruled in the Oil Platforms case (Merits) that a use of force against a single warship could also be classified as an ‘armed attack’ (see here para 51). There are no specific and objective criteria in international law to determine the requisite threshold of gravity and, for this reason, the parties’ assessments may differ. Article 2 recognizes this fact by requiring a joint determination of whether an armed attack exists.  

Second, whether an armed attack by non-state actors would trigger Article 2 remains open. France has relied on the right to self-defence including collective self-defence to justify the use of force against non-state actors in the territory of third states (see here in relation to Daesh), and was more forthcoming in its statement at the Security Council Arria Formula Open Meeting of February 24, 2021 (see here at 35). Greece’s position is not known, but this question is not yet settled under international law with states taking different positions or not expressing their views.

Third, the question of whether the parties can take preventive collective self-defence action against a future armed attack has been answered in the negative to the extent that according to the wording of Article 2 collective self-defence is triggered when the ‘armed attack’ is underway (une aggression armée survient), emulating the English wording of Article 51 of the Charter which uses the word ‘occurs’. This implies a temporal limitation to the exercise of self-defence. It is also in line with the views of the majority of states (see here paras 188-191) and otherwise would have stretched quite dangerously the scope of collective self-defence. Article 2 also seems to circumvent the question of anticipatory self-defence and in particular the question of imminence by requiring an ongoing armed attack. It thus opts for the criterion of immediacy which is narrower than that of imminence. By stressing the temporal and indeed immediate nature of the armed attack, Article 2 also rejects other – factual, political, military, capacity-related – considerations in the construction of an armed attack (see here).

Fourth, according to Article 2 of the Treaty, the ‘armed attack’ must take place against the parties’ territory. This means that the scope of collective self-defence under Article 2 is narrower than that provided in Article 51 of the UN Charter and customary international law according to which there should be an armed attack against a State. Indeed, France issued a statement confirming that Article 2 concerns the territories of the two parties (see here). The location of the armed attack according to Article 2 can thus be the land, subsoil, territorial sea, and airspace of one of the parties, namely physical spaces under their sovereignty, as well as persons and objects of one of the parties within these spaces. Article 2 will also cover naval blockades of the territory of the parties (see here Article 3 (c)). Areas or maritime zones where each party exercises ‘sovereign rights’ and/or prescriptive or enforcement jurisdiction, for example, the exclusive economic zone and the high seas, are excluded. What Article 2 also excludes are attacks on persons or objects located outside the territory of the parties for example attacks on warships on the high seas or EEZ or armed forces located outside their respective territories. In this respect, the right to collective self-defence under Article 2 is also more narrow than that provided by Article 5 NAT read in conjunction with Article 6 NAT (see here). Still, a related and critical question is whether France and Greece accept each other’s determination of what falls within their territory in view of the fact that the extent of the airspace or territorial sea of one of the parties may be disputed. One could say that by signing the Treaty the parties accept each other’s determination of what constitutes their sovereign territory but the requirement of joint determination in cases of an armed attack leaves the parties some leeway.

If Article 2 is not triggered because of its geographic limitations, the fall-back provision is Article 51 of the UN Charter and Article 5 NAT.

The next question to consider is whether Article 2 is compatible with the NAT (see here). According to Article 8 NAT members undertake ‘not to enter into any international engagement in conflict with this Treaty’. We contend that the collective self-defence undertaking of the parties under Article 2 is compatible with NAT. First, Article 5 – NATO’s collective self-defence provision – does not abolish the right of NATO member states to individual or collective self-defence nor does it prevent NATO member-states from entering into other defensive or mutual assistance agreements. Member states still retain their inherent right to individual or collective self-defence against attacks by third states or by other member states although the rebuttable presumption is that member states will not attack each other. Second, and relatedly, Article 8 NAT does not establish the primacy of NAT obligations neither does it invalidate conflicting agreements. Third, Article 2 of the Treaty is not directed against NATO or against any of its member states but reaffirms an inherent right. Fourth, the Treaty between Greece and France does not prevent the parties from fulfilling their obligations towards NATO. For example, it does not impose an obligation not to provide assistance to any other NATO member state if it falls victim of an external armed attack. It should also be noted that in any case Article 5 NAT does not impose on member states a duty to provide defensive assistance. Fifth, Article 5 NAT does not contain a definition of an ‘armed attack’ that would be violated by a contrary determination under Article 2 of the Treaty. Sixth, NATO determinations as to whether an armed attack has occurred are made on a case by case basis by NAC whose decisions are consensual and do not create as such any legal obligation, although a good faith obligation to at least not frustrate the decision can be presumed. Since Greece and France are also NATO members, they can use NATO’s decision-making process either to frustrate the decision by breaking their silence or to opt out. Finally, Article 2 is not incompatible with Article 6 NAT which defines the location of the armed attack more broadly. This is lex specialis applying only to collective self-defence instances falling under the NAT.

In conclusion, both Article 2 and Part III of the Treaty are compatible with the parties’ obligations under the UN Charter and NAT. The Treaty appears to meet certain political, security, military, and economic expectations of the parties. For Greece it achieves an upgrade of its armed forces by purchasing state-of-the-art warships and military aircraft and more importantly it establishes a bilateral collective self-defence alliance as a deterrent against the growing assertiveness of Turkey and outright threats in relation to disputes over maritime zones in the Aegean and Eastern Mediterranean. Indeed, Turkey has expressly stated that it shall treat as casus belli an extension of the Greek territorial sea from the present 6 miles to 12 miles (see here). For France, the Treaty is the basis of a lucrative 10 billion Euros arms sales agreement, it projects France as the leading military power in the EU after Brexit and secures military cooperation in areas where French armed forces are actively engaged, such as the Sahel (see here Article 18 of the Treaty which provides ‘Cette cooperation [militaire], sans que cela soit limitative, peut prendre les forms suivantes: … j) Participation à des deployments sur les theatres d’ operations dans le but de soutenir des interest communs, telles les operations menées par la France au Sahel).

From an international law perspective, the parties’ practice or common positions will contribute to the development as well as clarification of the law on collective self-defence.