President Donald Trump on Saturday followed through with his threat to impose new tariffs on the United States’ two biggest trading partners, Mexico and Canada, whose leaders immediately announced steps to fight back.

“We need to protect Americans, and it is my duty as President to ensure the safety of all,” Trump said in a post on social media, in which he described the tariffs as a way to pressure the countries into doing more to stop the flow of illegal drugs and undocumented immigrants.

Trump said most goods from Mexico and Canada will see a 25% surtax, except for Canadian oil, which will see a 10% tariff. He also said he was imposing a new 10% tariff on goods from China on top of existing duties.

The tariffs won’t go into effect until just after midnight on Tuesday morning, however, leaving open a small window that could be used for a negotiated solution.

Tariffs are charges placed on imported goods as they enter the country, paid by the company or individual bringing the good in. Economists are almost unanimous that tariffs are passed on to the consumer as higher prices.

Whether Trump’s gambit will succeed is unclear, but the potential costs to the US economy could be huge, either in terms of higher prices for American consumers or via retaliatory measures that would mark the beginning of a continental trade war.

Canadian Prime Minister Justin Trudeau in a........

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