so, have canadian producers undercut the market by crashing prices and balance it with a government subsidy to local oil producers (i don't like that in general, but...) rather than a retaliatory tariff. the debt will go up, but the price of oil will come down across the board, and that will balance out to no increased revenues by the americans. then, sue them to pay for it.
this will make other markets more attractive than the united states, as well, and production will shift.
if you take that approach, the americans will pay for their own tariffs, in the long run.