Donald Trump is imposing 25% tariffs on imports from Canada and Mexico and 10% tariffs on goods from China.
The move raises fears of price increases for US consumers as the American president suggested he would try to blunt the impact on oil imports.
He has been threatening the tariffs to ensure greater co-operation from the countries on stopping illegal immigration and the smuggling of chemicals used for fentanyl.
And he has also pledged to use tariffs to boost domestic manufacturing.
Analysis by economics and data editor Ed Conway:
Trump’s changed tack to focus tariffs on Mexico and Canada – why?
“Starting tomorrow, those tariffs will be in place,” White House press secretary Karoline Leavitt told reporters on Friday.
“These are promises made and promises kept by the president.”
The tariffs carry both political and economic risks for Mr Trump.
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Many voters backed the Republican on the promise that he could cut inflation, but tariffs could trigger higher prices and potentially disrupt the energy, car, lumber and agricultural sectors.
Mr Trump had said he was weighing issuing an exemption for Canadian and Mexican oil imports.
“I’m probably going to reduce the tariff a little bit on that,” Mr Trump said.
“We think we’re going to bring it down to 10%.”
