Threats by President-elect Donald Trump to impose U.S. tariffs on its immediate neighbors appear to have created a split between Canada and Mexico, after Canadian officials said problems with the two countries' borders were not comparable.

The number of migrants caught illegally crossing the U.S. borders with Mexico and Canada fell in November, a senior U.S. border official told Reuters, part of a months-long trend that undercuts President-elect Donald Trump's claim illegal immigration is out of control.

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.