Momentum seems to be shifting to Ukraine on eastern Europe’s bloody battlefields. But Russia still has the resources to ride out a long war, despite US-led sanctions meant to starve the marauding nation and its president, Vladimir Putin, of warmaking capability. After Russia invaded Ukraine in February 2022, the United States and many allies imposed sanctions on Russia widely touted as some of the toughest ever. They’ve tightened over time and now include limits on Russia’s ability to bank with the outside world, a ban on many technology imports to Russia, boycotts of Russian energy products, and a price cap...