A government official says Canada is already examining possible retaliatory tariffs on certain items from the United States should President-elect Donald Trump follow through on his threat to impose sweeping tariffs on Canadian products.

The president-elect said that he would impose the across-the-board tariffs on Day 1 and that they would stay in place until Canada, Mexico and China halted the flow of drugs and migrants.

Donald Trump has announced 25% tariffs on Mexico and Canada. Here is how they would work and what such tariffs might mean.