President Donald Trump reportedly elicited gasps from the international crowd gathered at the World Economic Forum in Davos, Switzerland, on Thursday when he suggested that Canada could become a U.S. state in order to avoid the sweeping tariffs he wants to impose.

"If you don’t make your product in America, which is your prerogative, then very simply, you will have to pay a tariff."

The president complains of a "tremendous" trade deficit with its neighbour, saying the US does not need Canadian energy, vehicles or lumber.