President-elect Donald Trump on Monday promised massive hikes in tariffs on goods coming from Mexico, Canada and China starting on the first day of his administration, a policy that could sharply increase costs for American businesses and consumers.

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.

While the announcement is almost certainly bluster to bring attention to illegal immigration and fentanyl smuggling, there are several reasons why it is so risky.