In a series of executive orders on Tuesday, US President Donald Trump wrote that "Canada is discriminating in fact against the commerce of the United States," and ordered the ban, which comes into effect on 29 September.
Earlier on Tuesday, Canada Prime Minister Mark Carney said in a video address that Canada's pivot away from the US as its largest trading partner "will come at a cost".
Both US and Canadian officials have said they would like to strike a deal, but no new talks have been scheduled since negotiations collapsed in late August.
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