Mike Lewis has a guest post at Just Security today responding to Ryan Goodman’s recent post exploring what the US’s claimed “unwilling or unable” test for self-defence against non-state actors means in the context of Syria and ISIS. Ryan, careful scholar as always, rightly points out that the test “remains controversial under international law.” Mike doesn’t seem to have any such qualms, but that’s not what I want to respond to here. Instead, it’s important to note that Mike makes a basic error concerning how the “unwilling or unable” test functions — assuming for sake of argument it is a valid approach to self-defence under Art. 51 of the UN Charter (emphasis mine):
It is important to note that this interpretation does not give the US unlimited license to act in violation of the sovereignty of other states as some opponents of the standard claim. There are limits and dangers associated with taking such a course of action. First of all, an intervening state can only take such actions after giving the host/target state a meaningful opportunity to prevent its territory from being used by the non-state actor to launch attacks. In the case of Syria, there is no question that it is unable to control the territory under ISIS control so further delays are unnecessary. Secondly, the intervening state does so at its own peril. Syria can rightfully interpret any strikes as aggression by the US and it is justified in taking steps to prevent such attacks and to destroy the drones/aircraft conducting such attacks.
Um, no. The entire point of arguing self-defence — in any form, including pursuant to the controversial “unwilling or unable” test — is that it cures any violation of state sovereignty under Art. 2(4) of the UN Charter. So if the US attacked ISIS in Syria because Syria was unwilling or unable to prevent ISIS from using its territory as a base for attacks, the US would not violate Art. 2(4) and Syria would have no right whatsoever to act in self-defence against that armed attack. Indeed, any attempt to “prevent such attacks and to destroy the drones/aircraft conducting such attacks” would represent an act of aggression by Syria against the US, thereby opening the door to legitimate acts of self-defence against Syria itself.
Again, I don’t accept that the “unwilling or unable” test reflects current customary international law. But it’s important not to let that debate obscure how self-defence functions under Art. 51 of the UN Charter.