alt Hacker NewsTarriffs will hurt your existing industries, they will lose sales/revenue.
Since you are getting hurt you play tit-for-tat to get the other to knock it off.
So you add export taxes to items they care about (oil/fertilizer/...) and compensate the losses incurred by existing industries.
You also add tarriffs on items that have alternatives, like alcohool.
Maybe add tarriffs on items with elastic prices, say 100% tarriff on digital services. Software services will have to adjust prices so they end up the same after tarriffs since few people will accept youtube or netflix doubling in price.
This hurts both countries but will get a result - either free trade or no trade.
In the meanwhile, Trump's entourage has derivative bets on this and take massive proffits shorting everyone. For them, this is all massively profitable.
Import tariffs and export tariffs have approximately equal influence on your economy. That's known as Lerner Symmetry. (A very narrow version of this can be proven in a mathematical sense, but the empirical effect is broader.)
For bilateral trade it doesn't matter much whether country A imposes import tariffs or country B exposes export tariffs.
Basically, the whole talk about retaliatory tariffs is silly.