US markets seesawed Tuesday after another tariff roller coaster ride. President Donald Trump doubled down on his threat to levy a new round of hefty tariffs on Canada earlier in the day, but officials from both countries Tuesday afternoon said they would meet this week to deescalate the tensions.

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.