Canada is preparing for U.S. President Donald Trump to hit the country with potentially devastating tariffs on Tuesday, but the federal government and the premiers say they are in the dark about what will actually materialize and how high those promised levies will be.

Tariffs on Canadian and Mexican goods imposed by the U.S. government are expected to take hold tomorrow, marking the start of a North American trade war.

U.S. President Donald Trump said 25 per cent across-the-board tariffs on imports from Canada and Mexico, with a lower 10 per cent levy on Canadian energy, will start Tuesday, tipping the continent into a trade war.