Most of the new duties kicked in Thursday, hitting countries with elevated rates that mark a departure from long-standing trade norms.

After months of threats, the United States government is now implementing the new tariffs driven by Donald Trump, affecting most countries worldwide and reigniting tension in international trade. Since his return to the White House in January 2025,

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.