The answer is in post 7. Period. Tax the crap out of everything from China and stop the tax when they deal with North Korea. When China has to pay for their wayward protege they will address him decisively.
This is a WAG on my part and only based on media coverage here and in China, but I felt like the Chinese Premiere may have viewed this crisis as a chance for China to step up as a responsible partner. It appears, another WAG on my part based on Chinese media, that he hit a brick wall when he returned home from his meetings with Trump. There remains a very powerful hard-line faction in China that seems to have a cold-war worldview and persuading them is the key.
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.