WASHINGTON — Whatever confusion people might have about President Trump’s agenda, his position on trade and manufacturing is crystal clear. “I believe strongly in free trade, but it also has to be fair trade,” he said in his address to Congress Tuesday night. He called for corporate tax reform and export incentives, and he lashed out at Nafta and China for draining America’s manufacturing base.

Mr. Trump’s stance on trade is one of his most popular positions, but many economists and policy makers are skeptical: They say that rapid automation will negate any gains made in bringing manufacturing jobs back, while the tariffs and other policies he has suggested using will ignite disastrous trade wars.

The doubters are wrong on both points. American manufacturing’s most advanced sectors remain big employers, and much of their payroll shrinkage stems from predatory competition from high- and low-wage countries, as well as offshoring by American multinationals. And the trade-war alarmists overlook the matchless, yet overwhelmingly neglected, leverage America holds over the global economy.

Although cheap, labor-intensive goods often come to mind when Americans think of job-displacing imports, the more capital- and technology-intensive segments of manufacturing have hardly been immune. Sectors like motor vehicles and parts, pharmaceuticals, telecommunications equipment, nonelectrical machinery (like machine tools, farm machinery and power-generating turbines) and industrial chemicals add up to nearly half of manufacturing’s enormous, chronic annual trade deficits nowadays.