North Korea said it successfully tested a miniaturised hydrogen nuclear device on Wednesday, claiming a significant advance in its strike capability and setting off alarm bells in Japan and South Korea. The test, the fourth time the isolated state has exploded a nuclear device, was ordered by young leader Kim Jong Un and successfully conducted at 10:00 am local time (0130 GMT), North Korea's official KCNA news agency said. "Let the world look up to the strong, self-reliant nuclear-armed state," Kim wrote in what North Korean state TV displayed as a handwritten note. The ...