North Korea’s Missile Success Is Linked to Ukrainian Plant, Investigators Say North Korea’s success in testing an intercontinental ballistic missile that appears able to reach the United States was made possible by black-market purchases of powerful rocket engines probably from a Ukrainian factory with historical ties to Russia’s missile program, according to an expert analysis being published Monday and classified assessments by American intelligence agencies. The studies may solve the mystery of how North Korea began succeeding so suddenly after a string of fiery missile failures, some of which may have been caused by American sabotage of its supply chains...