North Korea's foreign minister has accused US President Donald Trump of declaring war on his country and said Pyongyang had the right to shoot down US bombers.
Ri Yong-ho said this could apply even if the warplanes were not in North Korea's airspace.
The White House dismissed the statement as "absurd". The Pentagon warned Pyongyang to stop provocations.
A UN spokesman said fiery talk could lead to fatal misunderstandings.
Mr Ri's comments were a response to Mr Trump's tweet that the North Korean leadership would not "be around much longer" if they continued their rhetoric.
"The whole world should clearly remember it was the US who first declared war on our country," Mr Ri told reporters as he was leaving New York, where he had addressed the UN General Assembly on Saturday.
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