Amid warnings of price increases, Canada moved quickly to retaliate, China said it had planned countermeasures and Mexico said it would soon unveil its response.

The invoking of national security to unravel trade agreements could scramble the international trading system in China’s favor.

The president said the planned duties were a response to China’s failure to curb fentanyl exports.

New York Times reporters witnessed the dangerous fentanyl production process inside a secret lab in Culiacán run by Mexico’s most powerful criminal syndicate.

President-elect Donald J. Trump has threatened to impose tariffs on Canadian exports unless the country stops the flow of migrants and fentanyl to the U.S.

A global crackdown on fentanyl has led cartels to innovate production methods and test their risky formulas on people, as well as rabbits and chickens.