For decades, North Korea’s most potent insurance policy has been the threat it poses to Seoul, guaranteeing that any US move against Kim Jong-un’s regime would first exact an unbearable toll on the South. Now, a new Pentagon blueprint may have just offered that survival strategy Washington’s seal of approval. The new National Defence Strategy, presented to a Senate Armed Services Committee hearing on Tuesday, calls on Seoul to take “primary” responsibility for deterring North Korea, with...