President Trump has taken a whipsaw approach to tariffs, widening and shifting course in determining which countries and goods will be subject to them.

But across Mr. Trump’s political career, his case for tariffs has remained consistent, relying on a number of false and misleading claims to describe a global trade system that is “unfair” to the United States.

Although Mr. Trump abruptly announced on Wednesday that he would pause steep reciprocal tariffs for 90 days, a 10 percent “base line” tariff remains in place for most imports.

Here’s a guide to some of his most cited claims:

Inaccurate claims about his trade policies’ impact

What Was Said

This lacks evidence. Mr. Trump imposed a 10 percent tariff on nearly all imports from most of the world, except for Canada and Mexico, that went into effect on April 5.