President-elect Trump’s pledge to impose tariffs on Mexico and Canada threatens to upend decades of North American integration, a bumpy process that’s recast the two U.S. neighbors as providers of raw and finished goods for the world’s biggest economy.

Trump, who takes office on Jan. 20, said he would impose a 25% tariff on imports from Canada and Mexico until they clamped down on drugs, particularly fentanyl, and migrants crossing the border, in a move that would appear to violate a free-trade deal.

President-elect Donald Trump threatened to impose sweeping new tariffs on Mexico, Canada and China as soon as he takes office as part of his effort to crack down on illegal immigration and drugs. He said he would impose a 25% tax on all products entering the country from Canada and Mexico,