Tariffs imposed by US President Donald Trump on imports of steel and aluminium have taken effect in a move that will likely escalate tensions with some of the America's largest trading partners. The measure raises a flat duty on steel and aluminium entering the US to 25% and ends all country exemptions to the levies.

U.S. President Donald Trump's increased tariffs on steel and aluminum imports took effect on Wednesday as prior exemptions, duty free quotas and product exclusions expired, as his campaign to reorder global trade norms in favor of the U.

President Donald Trump escalated his trade war Tuesday, announcing on Truth Social that he will double the tariffs on steel and aluminum coming from Canada from 25% to 50% in retaliation for new trade restrictions put in place by the province of Ontario this week.