MIAMI — The oil tanker was navigating near the coast of Guyana recently when its location transponder showed it starting to zigzag. It was a seemingly improbable maneuver and the latest digital clue that the ship, the Skipper, was trying to obscure its whereabouts and the valuable cargo stored inside its hull: tens of millions of dollars’ worth of illicit crude oil.

What You Need To Know • The recent seizure of an oil tanker known as Skipper by the U.S. off the coast of Venezuela marks a dramatic escalation of President Donald Trump’s campaign to choke off Venezuelan leader Nicolás Maduro’s access to oil revenues • The tanker is part of the illicit “shadow fleet” that global energy powers, including Venezuela, Iran and Russia, use to sidestep U.S. sanctions • Analysts say the operat

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