President-elect Donald Trump has threatened tariffs of 25% on imports from Canada and Mexico until fentanyl and undocumented migrants stop flowing over US borders. Canada says it has a plan to boost border security — and points to US government data that show most of the problems come from Mexico.

Arrests for illegal crossings from Canada spiked in the last fiscal year, but remain a fraction of the number of those from Mexico.

A government official says Canada is already examining possible retaliatory tariffs on certain items from the United States should President-elect Donald Trump follow through on his threat to impose sweeping tariffs on Canadian products.