Since December, the U.S. has been stopping and seizing oil tankers traveling in and out of Venezuela. They are part of what is known as a ghost fleet — tankers that try to secretly move oil around the world, funding states such as Venezuela, Iran and Russia. Christiaan Triebert, a reporter on the Visual Investigations team, explains what these ghost fleets are and why their days might now be numbered. Guest: Christiaan Triebert, a reporter for The New York Times working on the Visual Investigations team. Background reading: U.S. forces seized its...