This article was originally featured in Foreign Policy, the magazine of global politics and ideas.

U.S. President-elect Donald Trump, the self-proclaimed “tariff man,” campaigned on the promise of ratcheting import duties as high as 60 percent against all goods from China, and perhaps 20 percent on everything from everywhere else. And he might be able to do it—including by drawing on little-remembered authorities from the 1930 Smoot-Hawley Tariff Act, the previous nadir of U.S. trade policy.

Trump’s tariff plans are cheered by most of his economic advisers, who see them as a useful tool to rebalance an import-dependent U.S. economy. Most economists fear the inflationary impacts of sharply higher taxes on U.S. consumers and businesses, as well as the deliberate drag on economic growth that comes from making everything more expensive. Other countries are mostly confused, uncertain whether Trump’s tariff talk is just bluster to secure favorable trade deals for the United States, or if they’ll be more narrowly targeted or smaller than promised. Big economies, such as China and the European Union, are preparing their reprisals, just in case.

What makes it hard for economists to model and other countries to understand is that nobody, even in Trumpworld, seems to know exactly why tariffs are on the table. Trump himself has suggested using tariffs as a replacement for the entirety of U.S. federal-income-tax revenue; at the very least, Trump and his brain trust are relying on enhanced tariff revenue to offset the falling revenues that will come from a renewal of his 2017 tax cuts, which are set to expire next year and are an early priority for the incoming administration. Congress could include its own tariffs as part of the tax bill, or it could defer to Trump and his own authority to raise tariffs.

Either way, they appear to be coming.

It’s such an early priority, and tariffs are such a clear way to help pay for those tax cuts, that Trump’s former national security adviser John Bolton puts an early tariff-induced trade war at the top of his list of immediate concerns. “The first thing that worries me are the tariffs. We could have an economic crisis in the first six months of the administration,” he said.

But tariffs are also touted by Trump’s trade sherpas, such as former U.S. Trade Representative Robert Lighthizer, as a way to force manufacturing back to the United States by discouraging pricier imports. The more that plan works—and tariffs are a notoriously slow and inefficient way to juice domestic manufacturing—the less tariff revenue there will be.

And yet, tariffs are also described by those around Trump, and often seen as such abroad, as little more than a negotiating ploy to........

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