Narrowing Down the U.S. International Legal Theory for ISIS Strikes in Syria

By Ashley Deeks
Friday, September 12, 2014, 10:08 AM

In late August, I suggested several possible theories the Administration might invoke to argue that the use of force against ISIS in Syria is consistent with international law. In the wake of President Obama’s speech on Wednesday night and supplemental Administration statements, do we know anything more about which theory or theories the Administration has picked?

We might, even though the President did not say anything directly about the issue. In particular, we know that the Administration is arguing in the domestic context that its actions are covered by the 2001 AUMF. As Steve (on Lawfare), Marty Lederman (at Just Security), and Deborah Pearlstein (at Opinio Juris) have analyzed, in making this argument the Administration seems to suggest that ISIS is al Qaeda.

Let’s assume that this is the best reading of how the U.S. Government has brought ISIS under the mantle of the 2001 AUMF. If so, the USG appears to be importing ISIS conceptually into the framework of its ongoing armed conflict with al Qaeda. As most readers know, the United States long has argued that it is in an armed conflict with al Qaeda as a group, and rejects the idea that it is only in a conflict with members of al Qaeda in fixed geographic locations such as Afghanistan. In John Brennan’s remarks at Harvard in 2011, he stated:

As the President has said many times, we are at war with al-Qa’ida. In an indisputable act of aggression, al-Qa’ida attacked our nation and killed nearly 3,000 innocent people.  And as we were reminded just last weekend, al-Qa’ida seeks to attack us again.  Our ongoing armed conflict with al-Qa’ida stems from our right—recognized under international law—to self defense.

An area in which there is some disagreement is the geographic scope of the conflict.  The United States does not view our authority to use military force against al-Qa’ida as being restricted solely to “hot” battlefields like Afghanistan.  Because we are engaged in an armed conflict with al-Qa’ida, the United States takes the legal position that — in accordance with international law — we have the authority to take action against al-Qa’ida and its associated forces without doing a separate self-defense analysis each time.  And as President Obama has stated on numerous occasions, we reserve the right to take unilateral action if or when other governments are unwilling or unable to take the necessary actions themselves.

That does not mean we can use military force whenever we want, wherever we want. International legal principles, including respect for a state’s sovereignty and the laws of war, impose important constraints on our ability to act unilaterally—and on the way in which we can use force—in foreign territories. (Emphasis added.)

So it seems quite possible that the USG’s international legal theory for using force against ISIS in Syria is the reliance on the ongoing armed conflict with al Qaeda. If the USG is following the “Brennan approach,” it does not believe that it needs to conduct a separate self-defense analysis against ISIS and determine that it has suffered an armed attack by ISIS (or that it faces an imminent threat thereof). It only must ask whether (a) it has the consent of the state in which it is contemplating the use of force; or, absent consent, (b) that state is unwilling or unable to suppress the threat posed by ISIS. Under its theory, it also need not assess the level of hostilities against AQ in any one state in order to conduct military operations there; it can consolidate different hostile acts by AQ, wherever they occur, to argue that the level of hostilities with AQ remains high enough that it continues to constitute a non-international armed conflict. This approach remains contested, particularly by those who believe that one must analyze levels of hostilities on a state-by-state basis, but the USG has asserted it for a decade.

Whether you find the “Brennan approach” persuasive as applied to ISIS depends on whether you buy the idea that ISIS is an AQ equivalent. If you don't buy the “link to or replacement for AQ” idea in the domestic AUMF context, you likely will be troubled by it in the international context as well.  If ISIS is its own group and is neither associated with nor a direct offshoot of AQ, then the USG should not, as an international law matter, treat its use of force against ISIS as part of the ongoing conflict with AQ.

This idea is a variant of the fourth option I mentioned in my earlier post.  There, I speculated that the USG might deem ISIS to be an associated force of AQAP, given some reported links between the two, but I noted that such an argument would hinge on facts not available to the public.  It turns out that the USG's approach may be more direct than expected - ISIS as AQ, rather than an associated force of AQ.

We cannot be certain that this is the USG’s theory. It may be relying – alternatively or additionally – on a collective self-defense theory: it is providing military support to Iraq against ISIS as Iraq exercises its right of self-defense against armed attacks by a non-state actor based primarily (or at least initially) outside Iraqi territory. In any case, the idea that ISIS is AQ certainly invites the United States to use the argument that the use of force in this context is simply a continuation of an armed conflict that has been underway for years.