While Secretary John Kerry appears to be trying to resuscitate the US-Russia deal in Syria, one issue worth considering is whether a major step in the US-Russia plan is permitted under international law. As announced by Sec. Kerry, a second stage of the plan would involve coordinated U.S. and Russian military strikes against ISIL and al Nusra. The legal question boils down to this: Is the United States legally permitted to coordinate military operations with Russia if it is highly likely or practically certain that Russia will engage in serious violations of the law of armed conflict in carrying out its part of the operations?

This issue has been discussed in a somewhat related context at Just Security by the highly respected Claus Kreß. In his post, Professor Kreß addressed the question whether the United States could accept Syria’s invitation to militarily coordinate strikes against ISIL given the Assad regime’s commission of war crimes. Here’s the key paragraph in Professor Kreß’s analysis:

To start with the first scenario, it is submitted, that a State must not rely on the legal title of “intervention by invitation” where the acceptance of the invitation by a “criminal regime” would amount, by virtue of the conditions attached to the invitation by the regime, to a violation of the duty not to assist another State in the commission of serious violations of international law, including war crimes and actions rising to the level of crimes against humanity. As I have detailed in a recent article, while States may continue to be reluctant consistently to assert this duty, it flows from the customary rules on State responsibility. In a very enlightening recent article, Professor Monica Hakimi has usefully connected this body of law with the concept of the Responsibility to Protect. Yet, whether the acceptance of President Assad’s condition of “coordinated action” would entail the high risk for the accepting State to become engaged in a course of conduct amounting to internationally wrongful assistance to Syria’s violations of international law, is not easy to say.

Professor Kres refers to “the customary rules of State responsibility” as the source for this legal prohibition. The elements of the relevant rule are fourfold:

  1. The State aids or assists another State in the commission of an internationally wrongful act;
  2. Such aid or assistance contributes to the commission of that act;
  3. The assisting State has intention to facilitate and/or knowledge of the circumstances of the internationally wrongful act; and
  4. The recipient State’s act would also be wrongful if committed by the assisting State.

An important caveat: One must appreciate the particular U.S. position on the third element of the rule. As Miles Jackson and I explain in a post, there is an ongoing debate in legal circles as to whether the assisting State must have an intention to facilitate the wrongful act. As we noted, “the United States, for one, stated its support for some element of intent (the exact contours of its expressed position are not clear).”

Miles and I also explained that there may not be much of a difference in the U.S. and other States’ views of the third element in a particular set of circumstances: when a State acts with knowledge that there is a practical certainty that the other State will engage in the wrongful conduct. We wrote:

Nonetheless, it is worth noting that the two positions may not be that far apart (as is often shown in domestic law on complicity). Even if intent were required, if the assisting State’s knowledge of the circumstances approaches something close to practical certainty that the principal wrong will occur, it may be possible to make an inference of intent. Professor Vaughan Lowe QC argues that “as a matter of general legal principle States must be supposed to intend the foreseeable consequences of their acts.” If this is right, whatever the assisting State’s overall purposes, if it knows that its assistance is significantly contributing to the commission of the principal wrong it may be legally responsible.

Finally, it is important to consider not simply what NGOs or the media report about Russia’s activities, but what U.S. officials are willing to say about Russia’s propensity to engage in internationally wrongful conduct in Syria. Operation Inherent Resolve spokesman, Col. Steve Warren said: “[T]he Russians have been indiscriminate, they’ve been reckless in Syria, they seem to have no difficulty dropping cluster munitions around where civilians may be.” Ambassador Samantha Power in her remarks outside the Security Council on Saturday night said: “Russia decided to join the Assad regime, escalating the conflict, and – perhaps worst of all – itself adopting some of the regime’s worst practices: hitting hospitals, hitting refugee camps, hitting markets without a single public expression of remorse.”

I do not offer many answers in this post. My objective here is more modest: to identify the relevant legal question and the framework for addressing it.