Though Donald Trump spoke of China during his campaign almost exclusively as the biggest threat to American prosperity, he appears to come away from his first sit-down with President Obama with an appreciation that a nuclear-armed North Korea is a “big problem for the country.”  If so, he may be only baby steps away from an appreciation that China – as North Korea’s only significant trading partner and diplomatic ally – holds the keys to any conceivable solution to that problem.  So at some point, he will have to ask:  Is China likely to help with North Korea if its products are subject to 35 percent tariffs?