The president-elect’s opening salvo in trade and border talks with the United States’ neighbors is casting a harsh light on the North American alliance.

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.

President-elect Donald Trump intends to follow through on his plan to impose sweeping tariffs on America’s top trading partners — a move that could come at a high cost to U.S. consumers. On Monday, Trump promised a new tariff on all products entering the U.