“We don’t have tariffs anywhere,” President Trump said in a recent interview with The Wall Street Journal. In fact, his administration this year has placed levies on more than $300 billion in imports.

Mr. Trump said he views tariffs as a trade negotiating tactic. “We don’t even have tariffs,” he said in the interview. “I’m using tariffs to negotiate. I mean, other than some tariffs on steel—which is actually small, what do we have? ... Where do we have tariffs? We don’t have tariffs anywhere.”

He...