Chaos in the Middle East has diverted Western eyes, but Kim Jong Un’s reign of terror in North Korea continues. Last month one high-ranking official was conspicuously absent from an important military funeral, leading to speculation of a new purge. On Oct. 10, North Korea marked the 70th anniversary of its ruling Workers’ Party with a military parade. “Our party can confidently state,” Mr. Kim said in a speech, “that our revolutionary armament today can deal with any kind of war U.S. imperialists ask for.”

It is time for the...