U.S. President Donald Trump has pledged to place 25% tariffs on imports from Mexico and Canada from Feb. 1 if the two countries are not judged to be doing enough to stop the flow of fentanyl into the United States.

General Motors, the largest producer of cars in Mexico, won’t provide details on how it would react if President Trump imposes 25 percent tariffs from the two countries.

Trump has shown a willingness to move swiftly on tariffs in recent days without allowing for drawn-out talks. On Sunday, Trump announced—and then backed off—a threat to impose