Nations targeted by President Trump’s tariffs on steel and aluminum decried the measures as unfair Tuesday and threatened to retaliate in a growing trade dispute that threatens to further roil economic markets and strain the United States’ relations with major allies.
Prime Minister Justin Trudeau of Canada, the United States’ biggest supplier of both metals, described Mr. Trump’s 25 percent tariffs on all steel and aluminum imports as “unjustified” and “unacceptable.”