The “sanctions war” between the West and Russia, the worst crisis since the end of the Cold War, again raises the issue of whether the imposition of economic sanctions without authorization of the U.N. Security Council is permissible under international law. In this Article, I analyze the legal justifications and contemporary sanctions practice of the United States, and the evolution of Russia’s arguments against the use of those economic sanctions. On the basis of a brief case study analysis of episodes related to the imposition of the tacit trade embargo upon Russia’s neighboring countries, I argue that while on political and diplomatic levels the United States and Russia demonstrate opposite views towards the legality of unilateral economic sanctions, today, at its very core, the actual activity of both states tends to make unilateral sanctions more recognizable as a part of international customary law.