President-elect Donald Trump is threatening to impose sweeping new tariffs on Mexico, Canada and China as soon as he takes office as part of his efforts to crack down on illegal immigration and drugs.

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

WASHINGTON—President-elect Donald Trump pledged that soon after taking office he will slap steep tariffs on Mexico and Canada, two of America’s closest allies, as well as China, the clearest indication since his election victory that he plans to follow through on the tough campaign rhetoric that helped propel him to the White House.