North Korea's fifth nuclear test prompts U.S. calls for more sanctions

By Jack Kim and Michelle Nichols SEOUL/UNITED NATIONS (Reuters) - North Korea conducted its fifth and biggest nuclear test on Friday and said it had mastered the ability to mount a warhead on a ballistic missile, ratcheting up a threat that rivals and the United Nations have been powerless to contain. The blast, on the 68th anniversary of North Korea's founding, drew a fresh wave of global condemnation. The United States said it would work with partners to impose new sanctions, and called on Chi