The problem with any increased duty on products from China is that such increased duty would by paid, not by the PRC, but by the American consumer, because most of our consumer good come form there, and it would take months for alternative manufacturing, supply and delivery chains to be put in place.
Agree on the downside, but how do we measure that versus a conflict and potentially staggering casualties on the peninsula to include our own forces?
There has to be a trade somewhere. On top of that, there is the reality that any conflict in Korea would create an economic disruption of its own as well.