Kim Jong-il, the North Korean dictator who made his isolated country a nuclear power, died on Saturday of a heart attack at age 69. State media kept the death a secret for nearly two days, suggesting a possible leadership vacuum. North Korea’s ruling Workers’ Party released a statement suggesting that Kim’s youngest son, Kim Jong-un, had succeeded his father. North Korea conducted a short-range missile test on Monday, according to unconfirmed reports from South Korea. David Sanger, chief Washington correspondent for The New York Times, and contributor to WQXR’s Washington Report, wrote about Kim’s death in Monday’s paper, and reports on the latest developments.