The U.S. will impose tariffs on steel and aluminum imports from Canada, Mexico and the European Union starting on Friday. Trump's ill-advised Tariffs Provoked Anger and Retaliation from US Allies.

The tariffs make good on President Donald Trump's threats and show the administration is maximizing pressure to win concessions from allies, while simultaneously negotiating through a high-stakes trade conflict with China, seen as an economic competitor.

Besides steel and aluminum, the U.S. administration is studying whether tariffs should be imposed on imported cars and auto parts under the same law that gives Mr. Trump wide authority to erect trade barriers under the banner of national security.