[stonesthrowaway]

> so in the event of effective sanctions on a country

That's the point. You can't effectively sanction china.

> where the tariff is effectively infinite making the amount supplied go to zero

There is a difference between a complete blockade and targeted sanctions.

> this should be even better for the country affected?

One causes a complete collapse of an economy (north korea) while the latter helps a nation build up a sector of an industry (china).

China is the top trading partner of most countries around the world. Even with these sanctions. Go figure. It would be like if china banned exports of 'rare earth minerals' to the US. It would only make the US stronger because we'd just invest in mining rare earth minerals.