North Korean nuclear test draws US warning of 'massive military response'

North Korea’s detonation of a sixth nuclear bomb on Sunday prompted the Trump administration to warn that even the threat to use such a weapon against the United States and its allies “will be met with a massive military response.’’

The test — and President Trump’s response — immediately raised new questions about the president’s North Korea strategy and opened a new rift with a major American ally, South Korea, which Mr. Trump criticized for its “talk of appeasement” with the North.

The underground blast was by far North Korea’s most powerful ever. Though it was far from clear that the North