President Donald Trump just enacted a new wave of tariffs on dozens of America’s trading partners, marking a substantial escalation in ongoing trade tensions that could constitute the biggest change to the global economy in nearly a century.

Olu Sonola, the head of U.S. economic research at Fitch Ratings, said the economy was just “starting to see” the effects of the tariffs that Mr. Trump announced in the spring, adding that with Mr. Trump’s newest duties now in place, Americans would “see that magnified” in coming months.

The U.S. began officially levying higher taxes on imports from dozens of countries Thursday, four months after President Donald Trump first announced plans to impose tariffs on most of the world while seeking new trade agreements across the board.