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.

MEXICO CITY — Mexico’s president responded angrily Tuesday to President-elect Donald Trump’s pledge to impose a 25 percent tariff on its products if the country didn’t curb the flow of irregular migrants and fentanyl, warning that the penalties would only wind up causing inflation and unemployment in the United States.