Canada is the largest exporter of steel and aluminum to the US. Will they retaliate with tariffs on things they import from the US?
To answer that I looked into what things the US exports to Canada, and it turns out that the three largest things they buy from us are vehicles, heavy machinery, and electrical machinery. Needless to say, all these things that use lots of aluminum and steel.
So Canada won’t have to retaliate; the price of US manufactured goods will rise relative to Canadian-made goods, not only Canada, but everywhere in the world.