North Korea's foreign minister has accused US President Donald Trump of declaring war on his country and said Pyongyang has the right to shoot down US bombers.
North Korean Foreign Minister Ri Yong-ho said they could shoot the the warplanes down even if they were not in North Korea's airspace.
The White House dismissed the statement as "absurd" and the Pentagon warned Pyongyang to stop provocations.
Mr Ri's comments were a response to Mr Trump's tweet that Mr Ri and North Korean leader Kim Jong-un 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.
"Since the United States declared war on our country, we will have every right to make counter-measures, including the right to shoot down United States strategic bombers even when they are not inside the airspace border of our country."
In his fiery speech on Saturday, Mr Ri had described Mr Trump as a "mentally deranged person full of megalomania" on a "suicide mission", which drew a response from the US president on Twitter.
Just heard Foreign Minister of North Korea speak at U.N. If he echoes thoughts of Little Rocket Man, they won't be around much longer!— Donald J. Trump (@realDonaldTrump) September 24, 2017
The two sides have been engaged in an increasingly angry war of words. Despite weeks of tension, experts have played down the risk of direct conflict between the two.
North Korea has continued to carry out nuclear and ballistic missile tests in recent weeks, in defiance of successive rounds of UN sanctions.
The country's leaders say nuclear capabilities are its only deterrent against an outside world seeking to destroy it.
After the North's latest and most powerful nuclear test earlier this month, the UN Security Council approved new sanctions on the country.
A UN spokesman warned fiery talk could lead to fatal misunderstandings.