US Defence Secretary Jim Mattis has reacted to North Korea's latest nuclear test by saying threats to the United States and its allies "will be met with a massive military response".
Mr Mattis spoke at the White House following a meeting with President Donald Trump and national security advisers. He said any response will be "both effective and overwhelming".
Mr Mattis said the United States is "not looking to the total annihilation" of North Korea, but added "we have many options to do so".
North Korea claimed "perfect success" in an underground test of what it called a hydrogen bomb - potentially vastly more destructive than an atomic bomb.
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It was the North's sixth nuclear test since 2006, but the first since Mr Trump took office in January.
