North Korea advised the US State Department of its intention to test a nuclear device prior to today's underground explosion, but did not say when it would conduct the test, department spokeswoman Victoria Nuland told Reuters.
Nuland said the notice came through "usual channels" but declined to say when Washington received the notification.
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Addressing an audience in America, the former PM said of Europe's single currency that it was not working "as intended".
The countries lawmakers voted to impeach President Park Geun-hye in the wake of mass protests against her.
The former presidential candidate, who has herself been the target of false news reports, said such stories had 'real-world consequences'.