The UN’s new sanctions package against North Korea (DPRK) may not have a significant impact on trade in the short-term. China accounted for 86% of DPRK exports in 2016, which had already fallen by 27% in the second quarter of 2017 on a year earlier. That likely reflects China abiding by an earlier ruling on coal exports from North Korea. Yet, China’s exports to DPRK (of which only 58% were food last year) have increased by 17% on a year earlier. As a consequence the DPRK already had a $1 billion trade deficit with China in the past 12 months. It isn’t clear how that was being funded, but...