North Korea, the world’s nuclear-armed auto dealership from hell, is turning up the high-pressure sales tactics. After months of charm that had secured Kim Jong Un a summit with President Trump in Singapore next month, Mr. Kim has now pivoted without warning. Pyongyang canceled meetings with South Korea, complaining of military exercises with the U.S., which Washington promptly called off at Seoul’s request. North Korea is also threatening to scrap the Singapore parley unless denuclearization is taken off the agenda.
There’s...