Recent reports that Russia is using its military might to assist Syrian forces in defeating rebel groups trained by the United States have prompted concerns about the effectiveness of the United States’ strategy in Syria. Attacks by Russian forces also create risk of direct conflict with United States and other nations who are assisting Iraq and Turkey in defeating ISIS. But there is an additional risk to the international strategy to defend Syria’s neighbors from ISIS attacks. Russian assistance to Syria may negate the international legal basis on which the United States, Australia, Turkey, Iraq, and others have justified their intervention in Syria.
For those states, the international legal basis for using force in Syria against ISIS is based on the “unwilling or unable” theory (expertly analyzed by Ashley Deeks here). Under the United Nations Charter, there is a general prohibition on the “use of force” against the territorial integrity or political independence of a state. There is an exception under Article 51 when a state is the victim of “an armed attack.” But that exception has a twist with Syria. Iraq and Turkey were not attacked by Syria, but by ISIS, a non-state actor attacking from within Syrian borders. Iraq and Turkey can clearly use armed force within their borders to defeat ISIS, but what about using military force inside Syria to stop ongoing or imminent attacks by ISIS? Can Iraq and Turkey violate the sovereignty of Syria to protect themselves from an attack from a non-state actor? Can other nations assist under a collective self-defense theory to conduct attacks inside Syrian territory?
Enter the unwilling or unable theory, which allows Iraq and Turkey to defend themselves, even by launching attacks within the territory of Syria, if the Syrian government is “unwilling or unable” to stop the attacks. While some academics dispute whether the unwilling and unable standard is firmly established in customary international law, various states are relying on the unwilling or unable theory as a legal basis for their in Syria. The U.S. Ambassador to the United Nations specifically cited the “unwilling and unable” standard as the international law basis for the U.S. and international intervention inside Syria. Until recently, it was clearly met, because Assad has shown himself to be unable to defend his own country from ISIS, let alone stop ISIS from attacking his neighbors.
Now enter Russia. Russia has the capability to assist Syria in defeating ISIS. Russia is clearly “able.” The only question is whether Syria and Russia are “willing” to focus their efforts on stopping ISIS from attacking Syria’s neighbors. In other words, Syria and Russia have two ways to prohibit the United States and others from using force in Syria. Right now they are using a direct approach, by attacking rebel groups that are supported by Turkey, Iraq, the United States, and others in that coalition. But if Syria and Russia commit themselves to attacking ISIS to prevent ISIS from attacking Syria’s neighbors, and – importantly – actually attempt to do so, the international community would lose its legal basis for using force inside Syria against ISIS over the wishes of the Syrian government.
The United States and others who are acting in collective defense of Iraq and Turkey are in a precarious position. The international community is calling on Russia to stop attacking rebel groups and start attacking ISIS. But if Russia does, and if the Assad government commits to preventing ISIS from attacking Syria’s neighbors and delivers on that commitment, then the unwilling or unable theory for intervention in Syria would no longer apply. Nations would be unable to legally intervene inside Syria against ISIS without the Assad government’s consent.
Major Patrick Walsh, is an Associate Professor in the International and Operational Law Department at the US Army’s Judge Advocate General’s Legal Center and School in Charlottesville, Virginia. The views expressed herein are those of the author and do not reflect the official policy or position of the US Army, Department of Defense or the US Government.