Is the Art. 5 Doomsday Scenario Plausible?

I have seen a number of suggestions recently in the media that Turkey’s invasion of Syria could lead to NATO being dragged into the conflict as a result of Art. 5 of the NATO treaty. Art. 5 provides, in relevant part, as follows:

The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.

The idea seems to be that if Syrian forces attack Turkish forces that are fighting (read: trying to exterminate) the Kurds, Art. 5 would require NATO to come to Turkey’s aid. Here, for example, is a statement by Luxembourg’s Foreign Minister:

Alliance members are increasingly concerned that the situation could develop into an Article 5 scenario if the Syrian army or allied actors respond militarily to the Turkish offensive.

Article 5 of the North Atlantic Treaty states that an attack on a NATO country is to be treated as an attack on all NATO countries, which could potentially trigger a common response.

Luxembourg’s Foreign Minister Jean Asselborn warned in an interview with German broadcaster BR that more countries could be drawn into the war.

“For me, it is very alien what happens there. Imagine Syria or allies of Syria strike back and attack Turkey,” Asselborn told BR.

“In German, this means that if all of NATO countries were attacked, then they would have to step in to help Turkey, which is why I say alien.”

This would indeed be a doomsday scenario — but I don’t think it’s particularly likely. Art. 5 is a collective self-defense provision that is only triggered by a NATO member’s individual right of self-defense. That is critical in the Syrian situation, because it means that NATO would not have to come to Turkey’s aid simply because Syria launched an armed attack against Turkey. Syria’s attack would also have to be unlawful, permitting Turkey to act in self-defense. If Turkey had to act in self-defense against a Syrian attack, NATO would indeed have to come to Turkey’s aid.

But here’s the thing: barring some kind of wildly disproportionate attack on Turkey, it is very unlikely that a Syrian attack on Turkish forces would entitle Turkey to act in self-defense. And that is because, as Claus Kress noted yesterday in an excellent post at EJIL: Talk!, there is no justification under international law for Turkey’s invasion of Syria in the first place:

Under international law, the right of self-defence exists if an armed attack against another State occurs. In such a case, cross-border defensive forcible action is permissible to the extent that the action is necessary and proportional to counter the attack. The existence of a right of anticipatory self-defence has long been controversial. An arguable case can be made that such a right exists if an armed attack against a State is imminent. It is also a matter of fierce debate whether a right of self-defence exists in case of a non-State armed attack and whether it may justify forcible defensive action on the territory of another State. An arguable case can be made that such a right exists where a State is either unwilling or unable to prevent a non-State group from conducting a large-scale cross-border armed attack from the territory of that State – under strict conditions of proportionality.

Even on the basis of such a broad understanding of the right of self-defence, which is being fiercely rejected by a significant number of States and by a significant number of highly respected international lawyers as being unduly permissive, it is impossible to see how Operation ‘Peace Spring’ could be justified under international law. The alleged ‘harassment fire’ by Kurdish units is being referred to in the Turkish letter in such a vague form that it is almost impossible to be verified. Even assuming there had been cross-border Kurdish ‘harassment fire’ at some point or points in the past, it is not apparent how this could reach the intensity threshold for a non-State armed attack. Even less is it apparent how Turkey’s massive use of force could be necessary to counter such ‘harassment fire’. No surprise then that Turkey neither uses the crucial legal term ‘armed attack’ in her letter nor claims that she has taken action in response to an (ongoing) armed attack. Rather, Turkey essentially rests her case on the need ‘to counter an imminent terrorist threat’. But her letter does not even begin to substantiate her claim that, at the material moment in time, a cross-border armed attack by Kurdish forces was imminent.   

Put more simply, Turkey is the aggressor in Syria, not the victim — a fact that becomes increasingly obvious with each passing day, as Turkey’s actions become more and more disproportionate to any “armed attacks” the Kurds might previously have launched from Syria. And that means Syria currently has every right to use force against Turkey in self-defense, its permissible actions limited only by the principles of necessity (unlikely to be an issue if Syria responds) and proportionality.

It is one of the few universally accepted principles of the jus ad bellum that there can be no self-defense against self-defense — a principle that dates back to the Ministries case after WW II. A Syrian attack on Turkish forces designed to repel the invasion, therefore, would not entitle Turkey to act in self-defense. And because Turkey would not be entitled to act in self-defense against a Syrian attack, NATO would have no obligation under Art. 5 to assist Turkey if Turkey used force against Syria anyway.

There are many reasons to fear the consequences of Turkey’s actions in Syria. A metastasized conflict in which NATO fights on the side of Turkey against Syria isn’t one of them — at least for now.

PS: It is also worth noting that Art. 5 doesn’t require NATO to use force on behalf of a member that suffers an unlawful armed attack. It must only take actions that it collectively “deems necessary” to come to the attacked member’s aid. So even if Art. 5 did somehow apply, NATO could still refuse to fight against Syria on Turkey’s behalf. (Julian has previously made this point in the context of ISIS’s 2015 Paris attacks.)