Bad idea.

Mr Trump tweeted that the US had been “decimated by unfair trade and bad policy”. He said steel imports would face a 25% tariff, and aluminium 10%.

However, critics argue that the tariffs would fail to protect American jobs and would ultimately put up prices for consumers.

Mr Trump’s announcement hit US markets, with the Dow Jones index closing down 1.7%.

Allow Mr. Friedman to explain: