“It’s opening markets that’s the key, not closing ours,” says Smith.

FedEx’s chief speaks from experience. The company he founded nearly 50 years ago does business in 220 countries, including China, and is now a $47 billion global powerhouse. FedEx is ranked number 58 on the Fortune 500 list of America’s biggest companies.

Speaking with Fortune’s Susie Gharib, Smith cautions about the economic risks of restricting trade with key U.S. trading partners like China. Getting tough on trade with China has been a central theme of the president’s “Make America Great Again” campaign. But Smith says it is important for President Trump to recognize “the value of open markets.”

“The average American family has a benefit from trade imports of almost $12,000 a year,” he explains. “If we don’t have those imports, TVs, cell phones, microwaves, appliances, and so forth, then our standard of living would be less by $12,000 per family of four.”

An even bigger risk, cautions Smith, is a severe economic downturn in the U.S. if the Trump Administration adopts a tough stance with its biggest trading partners. He cites the lessons learned from the Smoot-Hawley Tariff Act of 1930 which instituted high tariffs on imports and led to the Great Depression.

Could we see a repeat? “Absolutely,” says Smith. He quotes a study showing that severe trade restrictions would cause five million Americans to lose their jobs. “That,” he says, “is not a good policy.”