The sudden diplomatic escalation came more than two weeks after Kim Jong-nam, the long-exiled half brother of North Korea’s ruler, was killed in a poison attack at the Kuala Lumpur airport. “I can’t think of anything like this” happening for years, said Lalit Mansingh, a New Delhi-based scholar and long-time top Indian diplomat, said of North Korea’s directive. “This is way out of normal diplomatic practice.”