Prior to the U.S. attacks that dislodged president Nicolas Maduro of Venezuela, American forces have for weeks been blockading U.S.-sanctioned ships carrying Venezuelan oil. In mid-December, the United States began boarding, and seizing, tankers in the so‑called “shadow fleet” that move sanctioned oil across the globe, starting with stateless vessels. In a dramatic turn, this week the U.S. Coast Guard, with U.S. and allied military support, intercepted and boarded two Russian-flagged oil tank...