Canada’s ambassador to the United States said Sunday that Prime Minister Justin Trudeau was successful in getting President-elect Donald Trump and key Cabinet nominees to understand that lumping Canada in with Mexico over the flow of drugs and migrants into the U.

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.