Why, after NK's nuclear test, Trump aimed his sharpest fire at the south

In taking to Twitter to accuse Seoul of “appeasement,” Mr. Trump was venting his frustration at a new liberal South Korean government he sees as both soft on North Korea’s atomic program and resistant to his demand for an overhaul of trade practices that he views as cheating American workers and companies.

For Mr. Trump, the crisis lays bare how his trade agenda — the bedrock of his economic populist campaign in 2016 — is increasingly at odds with the security agenda he has pursued as president. It is largely a problem of Mr. Trump’s own making. Unlike several of his predecessors, who were able to press countries on trade issues while cooperating with them on security, Mr. Trump has explicitly linked the two, painting himself into a corner.