canada exports 98% of it's steel to the united states or mexico. if the united states asked us to put up a tariff on chinese steel, we probably should.
however, the policy may lead to inflation in electronics and other luxury goods.
i wouldn't expect that china would put up a tariff on, say, canadian wheat, as that would just hurt it's own people. chinese retaliation is likely to be outside of the realm of trade, but our relations with china probably couldn't get much worse than they've been recently, anyways.
i'm going to conclude that the steel tariff, in concurrence with an american tariff on chinese steel, is a reasonable policy.