President Trump on Monday declared that he would slap 25% tariffs on imported goods from Canada and Mexico starting on Tuesday, after weeks of speculation that the threat would be lifted or the rate lowered.

Trump said the tariffs would punish Canada and Mexico — partners in a trilateral trade agreement — for fentanyl trafficking. But he also said the move would encourage car manufacturers and other businesses to move their production to the United States.

“I would just say this to people in Canada or Mexico: if they’re going to build car plants, the people that are doing them are much better off building here, because we have the market where they sell the most,” Trump told reporters at the White House.

Trump is also set to add another 10% to tariffs on imports of Chinese goods, after initially applying tariffs of 10% last month.