- Video report by ITV News Security Editor Rohit Kachroo
The United Stated has called North Korea's allegations that the US declared war on Pyongyang "absurd".
“We’ve not declared war on North Korea. Frankly, the suggestion of that is absurd,” White House spokeswoman Sarah Sanders told reporters.
It comes after North Korea claimed it is authorised to shoot down US bombers in international airspace - in response to Donald Trump's "declaration of war".
Pyongyang's foreign minister said it interpreted the US president's latest aggressive rhetoric as a red-line threat against his country.
"The question of who won't be around much longer will be answered then," he added.
The White House later dismissed the interpretation of US intent, with Press Secretary Sarah Sanders declaring: "We have not declared war on North Korea."
It came as US bombers made a rare flight into international airspace east of North Korea at the weekend.
US Pacific Command said it was the furthest north of the DMZ, the strip of land running across the Korean peninsula, the planes had flown in the 21st century.
He has also fought an escalating war of words with North Korea leader Kim Jong Un as Pyongyang's missile testing continues in a bid for nuclear power.
Kim called Mr Trump a "mentally deranged US dotard" before Mr Trump replied that Kim was "obviously a madman who doesn't mind starving or killing his people".
ITV News Washington Correspondent Robert Moore said the North Korean minister's statement again brings Mr Trump's foreign strategy into question.
Mr Trump's signing on strict new restrictions on North Korean visitors is largely symbolic as so few make the journey.
The North Korean government prevents most of its 24 million population from travelling to foreign countries including the United States.
Exceptions include special cases like jobs that bring in foreign currency or sporting events.