Who pays for the terrible destruction wrought by war? This problem is far from new, but it is currently receiving renewed attention as a result of the war in Ukraine. The options currently available to states that are the victims of unlawful wars in the postwar era are limited. For Ukraine, some have proposed addressing this shortfall by seizing frozen Russian sovereign assets, and both the United States and Canada have passed legislation permitting just that. European officials have considered a similar proposal, but they have thus far rejected them as too legally risky. Indeed, such plans run afoul of the longstanding international law doctrine of sovereign immunity. Put simply, they attempt to cure one international legal violation by engaging in another.

In this Article, we offer another way forward for Ukraine and any other state that might find itself in this situation in the future: Ukraine may deploy what is known as the international law doctrine of countermeasures to freeze Russian sovereign assets in response to Russia’s injurious and illegal conduct against it. We argue that frozen assets need not be returned to Russia at the close of the war as long as Russia has failed to pay reparations. That is because the failure to pay reparations is itself an unlawful act for which countermeasures (continued freezing of assets) may be kept in place even if the unlawful war has ceased. Moreover, other states may join Ukraine, putting in place collective countermeasures, sometimes called “third-party” countermeasures. However, we argue against using countermeasures doctrine to simply seize Russian assets; such seizures would not properly qualify as countermeasures and thus would violate international law.

This approach to countermeasures, if adopted, could have implications beyond Ukraine, extending not only to future war reparations but also to international responses to cyber operations, human rights violations, or violations of environmental law obligations. Indeed, the challenge of securing reparations for Ukraine must be addressed not as a one-off problem but as a systemic one. We should therefore seek a solution that will benefit not just Ukrainians but other similarly situated actors in the future. This is yet another reason that existing ad hoc legislative proposals to seize Russian assets are inadequate: They might provide money to Ukrainians now, but they will undermine the international legal system while doing little to help future victims. Keeping the larger picture in view is not only important as a matter of equity and justice. It is also in the best interests of Ukraine, which must maintain unprecedented levels of global support for its ongoing defensive actions and efforts to hold the architects of this illegal war accountable for the extraordinary harm they have done. This Article’s proposal for institutionalizing collective countermeasures meets this challenge, offering a way to reinforce the reparations obligation in circumstances beyond the present conflict.