I often hear the idea that the U.S. dollar is the means by which the U.S. implements sanctions. And since the U.S. dollar pervades all corners of the globe, the U.S. government's sanctions are uniquely powerful. For instance, Reuters reports that Russian resource giant Rosneft is shifting all its contracts over to euros in order to "shield its transactions from U.S. sanctions." Another version of this idea was recently floated by David Marcus, the head of the Libra payments project: "The future in five years, if we don’t have a good answer, is basically China re-wiring” a large part of the world “with a digital renminbi running on their controlled blockchain,” Marcus said. He warned about the prospect of “having a whole part of the world completely blocked from U.S. sanctions and protected from U.S. sanctions and having a new digital reserve currency” with no alternative." The shared assumption of both the Rosneft and David Marcus quotes is that the U.S dollar