Russia has skillfully managed to devote military support to the separatists in Eastern Ukraine. Just how much support — and what kind of support — is unclear, since Russia formally denies that they are directly involved in the ongoing hostilities there. Ukrainian officials have insisted that they have specific proof that Russian troops and their equipment have not only crossed the border into Ukraine but have also engaged Ukrainian government troops. It is not unreasonable to speculate that, but-for the Russian assistance, the conflict would have concluded long ago with a Ukrainian government victory over the rebels.
In the face of mounting evidence of Russian involvement, the rebels have claimed that Russian soldiers deployed in Ukraine are there voluntarily while on vacation. This is an obvious attempt to deny Russian liability, under basic rules of state responsibility, for the actions of the troops. The question is whether this argument holds any water.
First, it is unclear whether the statement is accurate. The world community does not have access to the W2s, or the Russian equivalent, for the soldiers — so if the rebel leaders are lying, the world would have no idea. I also find it hard to believe that Russian troops, or any government troops for that matter, would voluntarily place themselves in harms way for no compensation whatsoever. More likely they are receiving cash payments covertly.
Second, even if the claim is true, and the Russian commanders have officially placed the soldiers on vacation (or furlough), there is the additional issue that they are no doubt using Russian government equipment, as opposed to their private “home” materials. While individual soldiers might own personaI firearms, I find it hard to believe that Russian troops own their own armored personnel carriers that they keep in their backyards for “vacation” purposes.
Third, and perhaps most importantly, it is unclear what the legal consequences of these “vacation deployments” are even if they are true. The standard is whether the troops are under the control (either effective control or overall control depending on which standard applies) of the Russian government. Employment and monetary payments are just one way of exercising control, as is operational control. However, suppose Russia provides the rebels with 50,000 troops who are “volunteering” to fight with the rebels? Would this automatically entail that Russia has no control over the troops? It seems to me that control requires a richer formulation, one that is sensitive to the varying ways that states can engage in covert assistance across borders. Although states may attempt to deny responsibility for this assistance, this does not mean that international law should let them without suffering the consequences.
In Nicaragua, the ICJ concluded that the mere provision of financial or military assistance, standing on its own, is insufficient to generate state responsibility for the actions of the assisted troops (via direct imputation). This was (and is) a sensible precedent, because the basic contours of complicity requires that international law recognize the various ways that assistance can trigger responsibility. Even if Russia only organized and armed the troops, but did not directly pay them a salary, it would seem to me that this constitutes an illegal interference in Ukrainian domestic sovereignty (with regard to both political independence and territorial integrity), in violation of the UN Charter and customary international law (in much the same way as the ICJ concluded in Nicaragua).
Of course, all of this might be moot. It is possible that Russia is engaged in direct operational control over the rebels, with logistical coordination, air support, and satellite imagery, that unquestionably demonstrates their responsibility even under the effective control test. But at this point the facts are very much unknown.