The leaders of Mexico and Canada responded quickly, and in different ways. Justin Trudeau, Canada’s prime minister, jumped on the phone to Mr Trump to chat about the “intense and effective connections” between their countries. His deputy, Chrystia Freeland, released a statement about the importance of border security.

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.