Barack Obama warned Donald Trump about trouble from North Korea, and his prediction is coming true. With North Korea's missile tests and America's missile defenses, China says they're like trains accelerating toward one another. China itself feels threatened, and South Korea, where the defenses are being installed, has just kicked its president out of office. Meantime, North Korea's Kim Jung Un appears to have orchestrated the public assassination of his half-brother. Is all this building up to a regional crisis?