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.

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.

The tariffs, if implemented, could dramatically raise prices for American consumers on everything from gas to automobiles to agricultural products.