HE HAS ACTUALLY gone and done it. President Donald Trump had long threatened to impose hefty tariffs on Canada and Mexico, America’s two biggest trading partners. Last month, when they were first due to take effect, he offered both countries a last-minute reprieve. Now he is in no mood to play nice. As we published this, new tariffs were set to come into effect at 12:01am EST on March 4th. America will hit imports from its two neighbours with levies of 25%. For good measure, Mr Trump will also add another 10% tariff on Chinese goods, on top of the 10% charge he implemented last month, which itself added to tariffs imposed in his first term.