The United States and Russia have entered a new and dangerous moment.
On Sunday, a U.S. fighter jet shot down a Syrian warplane. On Monday, the Russian Defense Ministry announced that it has terminated its “de-confliction line” with the United States and will consider U.S. military aircraft operating West of the Euphrates River as legitimate targets.
The risks of escalation and direct confrontation have never been higher.
The U.S. and Russia seem to disagree about both the facts and the law. The U.S. claims that the Syrian warplane was attacking Syrian Democratic Forces, while Russia claims that the warplane was providing air cover for Syrian ground forces mounting an offensive against ISIS.
Since Russia and Syria tend not to distinguish between ISIS and other anti-regime armed groups, the two sides may agree on the underlying facts but characterize them differently.
In addition, the U.S. claims that it used the proper de-confliction line to de-escalate an earlier clash between Syrian and SDF ground forces. However, Russia claims that the U.S. did not use the proper de-confliction line before shooting down the Syrian warplane.
As for international law, the U.S. claims that it acted “in collective self-defense of Coalition partnered forces,” while Russia claims that the downing of the Syrian aircraft was “a cynical violation of Syria’s sovereignty,” “a flagrant violation of international law,” and “actual military aggression against the Syrian Arab Republic.”
Who is right?
To set the stage, consider the U.S. Central Command’s press release, which begins as follows:
SOUTHWEST ASIA — At approximately 4:30 p.m. Syria time, June 18, Pro-Syrian regime forces attacked the Syrian Democratic Forces-held town of Ja’Din, South of Tabqah, wounding a number of SDF fighters and driving the SDF from the town.
Coalition aircraft conducted a show of force and stopped the initial pro-regime advance toward the SDF-controlled town.
Following the Pro-Syrian forces attack, the Coalition contacted its Russian counterparts by telephone via an established ‘de-confliction line’ to de-escalate the situation and stop the firing.
At 6:43 p.m., a Syrian regime SU-22 dropped bombs near SDF fighters south of Tabqah and, in accordance with rules of engagement and in collective self-defense of Coalition partnered forces, was immediately shot down by a U.S. F/A-18E Super Hornet.
Ja’Din sits approximately two kilometers north of an established East-West SDF-Syrian Regime de-confliction area.
Such clashes were bound to happen eventually, if not here then near the US garrison at Tanf.
The U.S. claims to have shot down the Syrian warplane on Sunday in collective self-defense of Coalition partnered forces. Now, the United Nations Charter recognizes that States have an inherent right of collective self-defense. However, under the UN Charter, collective self-defense refers to defense of another state, not defense of non-state actors.
Of course, the SDF fights on behalf of the Democratic Federation of Northern Syria, which is not recognized as a state, even by the United States. So the U.S. claim that this strike is an exercise of collective self-defense of Coalition partnered forces seems not merely false but confused.
Relatedly, the U.S. sometimes acts in “unit self-defense,” that is, in defense of U.S. troops under armed attack. In many cases, unit self-defense is just a special case of national self-defense. After all, U.S. troops are organs of the state, so defense of the former may constitute defense of the latter.
Presumably, SDF fighters are not organs of the U.S., or any other state, so “unit self-defense” of them is not a form of individual or collective self-defense either.
Indeed, were the SDF a de facto organ of the U.S., under its direction and control, then its actions would be attributable to the U.S. under the law of state responsibility. In principle, that could include any war crimes committed by SDF forces. My guess is that the U.S. is not eager to claim all of the SDF’s actions as its own.
Often, the U.S. invokes self-defense without clarifying whether it refers to self-defense under the UN Charter, self-defense under its own national rules of engagement, or self-defense under its own national criminal law.
However, since the press release independently claims that the strike was carried out in accordance with rules of engagement , its separate invocation of collective self-defense must refer to something else, and the UN Charter is the most likely candidate. Indeed, even if the U.S. complied with its own national rules of engagement, this would hardly ensure compliance with international law.
The press release continues:
The Coalition’s mission is to defeat ISIS in Iraq and Syria. The Coalition does not seek to fight Syrian regime, Russian, or pro-regime forces partnered with them, but will not hesitate to defend Coalition or partner forces from any threat.
The Coalition presence in Syria addresses the imminent threat ISIS in Syria poses globally. The demonstrated hostile intent and actions of pro-regime forces toward Coalition and partner forces in Syria conducting legitimate counter-ISIS operations will not be tolerated.
The Coalition calls on all parties to focus their efforts on the defeat of ISIS, which is our common enemy and the greatest threat to regional and worldwide peace and security.
Now, if the Coalition’s sole mission were to defeat ISIS in Iraq and Syria, then it might have a novel but plausible legal position. On this view, the Coalition is acting in collective self-defense of its member states (including Iraq, for example) from imminent or ongoing armed attack by ISIS. Accordingly, the U.S. is not defending SDF forces for its own sake, but merely as a means of sustaining its collective self-defense of its member states.
Importantly, so long as the Coalition uses no more force than necessary and proportionate to achieve its legitimate defensive aims, Syria and its allies would have no legal right to interfere. After all, as the International Military Tribunal at Nuremberg proclaimed, “there can be no self-defense against self-defense.”
The most obvious problem with this rationale is that it is far from clear that the Coalition’s sole mission is to defeat ISIS. Both Rex Tillerson and Nikki Haley have indicated that regime change remains a U.S. strategic objective.
We should therefore question whether the SDF’s presence in Ja’Din was a necessary and proportionate means of achieving a legitimate defensive aim.
As for the SDF, its strategic objectives seem to include creating an autonomous region, if not an independent state. So, even if the U.S. partnered with the SDF exclusively to defend its member states from ISIS, the SDF may be pursuing its own agenda, exceeding what would be necessary and proportionate to defend coalition member states.
To the extent that SDF forces pursue their own political aims, rather than—or in addition to—the defensive aims of the coalition, defense of SDF fighters may not be a necessary and proportionate means of sustaining our own defensive aims.
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In plain terms, the U.S. may have a legal right to protect non-state partner forces who are exclusively “conducting legitimate counter-ISIS operations,” but has no legal right to protect non-state partner forces who are pursuing regime change or other political objectives.
There is no right of collective self-defense of non-state actors, and the right of collective self-defense of other states only justifies measures that are necessary and proportionate means of achieving legitimate defensive aims.
For this reason, among others, the mixed motives of the U.S.-led coalition and its non-state partners compromise the legal basis of their military operations and draw them into conflict with Russia—both legally and militarily.