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Early Sunday evening, a US Navy F/A-18 Super Hornet shot down a Syrian Air Force Su-22 that had just completed a bombing run targeting US-backed Syrian Democratic Forces (SDF) in the Raqqa region. The episode raises important questions under the U.N. Charter (see Adil Ahmad Haque’s analysis here). But what about U.S. domestic law?
From a domestic law perspective, the Su-22 episode draws attention to an important but often neglected topic: When is it proper to construe an AUMF, or Article II itself, as providing implicit authority to use force in defense of third parties?
This question is, of course, a subset of the general domestic law questions about the distribution of war powers in our system. Those questions have been aired extensively with respect to operations against the Islamic State, and in fact there is a hearing on this very subject before the Senate Foreign Relations Committee later this morning (watch it here). The narrower question about third-party self-defense has not been a significant part of that discussion, however, because the focus has been on the applicability of the 2001 AUMF to operations against IS. Extending operations to Syrian government targets based on the threat those targets pose to others is a different matter (though one that also was present to some degree a few months ago when the Trump administration authorized a one-off set of missile strikes against a Syrian airfield in response to the regime’s use of chemical weapons).
So let’s dive in, starting with some brush-clearing. Obviously, the Syrian government is not within the explicit terms of either the 2001 or 2002 AUMFs. Could it instead be categorized as an “associated force” engaged in hostilities against the United States or its coalition partners? Hardly. One might be able to argue that the Syrian government is engaged in hostilities against America’s coalition partners. But even if we accept that this indirect belligerency really should count for purposes of the statutory analysis, the important consideration here is that the Syrian government could not plausibly be depicted as “associated” with al Qaeda. The associated forces option has no application here.
What argument does this leave? This is where self-defense might enter the picture. That is, in fact, the argument actually mentioned in the coalition’s public statement on the Su-22 episode: self-defense—or, more specifically, “collective” self-defense on behalf of the SDF ground forces.
Caveat: it is not clear from the brief statement that this argument was put forward with intent to advance it as a domestic law argument; perhaps the author of that statement had in mind only the international law issues, or perhaps it was just a policy explanation not meant to represent a legal position. But nevermind that. Does it actually work as a domestic law argument?
It might help to start with a simplified hypothetical. Assume for the sake of argument that U.S. forces are attacked by a foreign military in a situation unconnected to any AUMF. I think it is fairly well-settled that some degree of self-defense authority exists in that situation, under Article II. The only hard question from this perspective is whether considerations of necessity and proportionality then govern the extent of the self-defense authority so provide (I think yes), and if so how those concepts might apply in practical terms.
Now change things a bit, such that the attack on U.S. forces arises in a setting where those forces are operating against other opponents under color of an AUMF. At first blush, it seems superfluous to ask whether we can read into that AUMF an implied authority for self-defense operations, given the existence of the Article II authority. But something does turn on this. If the authority flows only from Article II, then issues will arise under the War Powers Resolution clock if operations based on self-defense last for a long period of time (absent congressional authorization). If the self-defense authority instead is derived from an existing AUMF, however, that issue drops out.
So, it may matter whether a self-defense authority can be read into an AUMF. Can such a clause be read into the 2001 or 2002 AUMFs? Neither has an explicit one, but this cannot be entirely dispositive. The 2001 AUMF also does not have an “associated forces” clause either, yet the entire intervention against the Islamic State (and much else besides) is premised on reading such a clause into the statute. A “self-defense” clause is, if anything, a more-plausible way to think about implied authorization to use force in the scenario in which U.S. forces are authorized expressly by statute to deploy into hostilities against one opponent but then find themselves attacked by another. I think that one can fairly imply some degree of self-defense authority, then, absent statutory language restricting that reading.
Now, back to the harder question actually presented by the Su-22 episode. We are talking here not about self-defense where US forces have been attacked, but where a third-party has been attacked. Even if the Article II and AUMF analyses above are correct, then, they do not compel the conclusion that the Su-22 episode was authorized as a matter of domestic law. More is needed.
Two lines of argument come to mind. Option one is to, in effect, circumvent this entire issue by claiming that this particular use of force fell below the constitutional threshold of “war” and thus did not trigger a separation of powers analysis in the first place. This was the move the Obama administration made in the 2011 Libyan intervention, citing a combination of strong national interests, the limited nature of the military force at issue (especially the lack of ground commitments), and the limited risk of escalation. Setting aside whether that was a good argument as to our protracted air operations in Libya, I’m doubtful the argument works with the Su-22 situation given (a) the extensive U.S. ground presence in theater (especially if you include Iraq, which I think you must) and (b) the manifestly-high risk of escalation (including, of course, escalation with the Russians).
That brings us to option two. Option two is to confront the issue head-on, accepting that the war powers issue is indeed implicated here, but arguing that at least some forms of third-party self-defense should be recognized as falling within Article II’s reach (or the reach of an implied self-defense authority under the AUMF). My initial thoughts on this argument were skeptical. But I became less skeptical when I considered that not all third-party self-defense scenarios are equal.
At one extreme, you might have a third party with no specific tie to the United States. This would be the weakest scenario (note that it is an apt description of the scenario when the Obama administration appeared to invoke Article II third-party self-defense on humanitarian grounds when using air power to prevent the Islamic State from further attacking civilians trapped at Mt. Sinjar in 2014).
At the other extreme, however, you might have a third party that is an organized armed group operating in close coordination with the U.S. military in a combat setting. That is to say, the third party in question might be a coalition partner, and not just a nominal one but an active co-belligerent engaged in partnered operations on a single battlefield. That situation is far more compelling, in my view, and it is in fact the situation presented by the Su-22 episode.
Should it matter that the coalition partner is a non-state actor instead of a regular armed force answerable to another government? This might present a problematic wrinkle for a U.N. Charter Article 51 analysis, given Article 51’s express reference to a “Member of the United Nations.” But that is not relevant to the domestic law analysis. I see no reason why the sovereignty question should matter more than marginally to the analysis above, and think it probably should not matter at all.
My bottom line, then, is that third-party self-defense is a tricky doctrinal extension, but one that probably should be recognized at least in the specific scenario presented here: defense of a coalition partner in the context of integrated combat operations.