What to know as President Donald Trump imposes steep new tariffs on imports from Canada, Mexico and China, prompting retaliation and countermeasures.

Futures tied to the Dow Jones Industrial Average fell 622 points, or 1.4%. S&P 500 futures dropped 1.6%, while Nasdaq-100 futures lost 1.7%. Futures on the Russell 2000, the small-cap benchmark, lost 2.1%. The Cboe Volatility Index, Wall Street’s fear gauge, briefly spiked above 22 before trading around 20.

Business groups, economists and even some Republicans cautioned that new tariffs on goods from Canada, Mexico and China could undercut U.S. industry and the economy.