Kim Jong Un has told Donald Trump he will pay for his UN speech in which he threatened to destroy North Korea.
The dictator said it was a declaration of war, and called the US president 'mentally deranged'.
The North Korean leader said he was now considering a response, and threatened to 'tame' Mr Trump with fire.
He said that Mr Trump's speech at the United Nations on Tuesday had only convinced him that Pyongyang's nuclear programme must continue.
"His remarks... have convinced me - rather than frightening or stopping me - that the path I chose is correct and that it is the one I have to follow to the last.
"As a man representing the DPRK and on behalf of the dignity and honour of my state and people and on my own, I will make the man holding the prerogative of the supreme command in the US pay dearly for his speech."
He added: "After taking office, Trump has rendered the world restless through threats and blackmail against all countries in the world.
"He is unfit to hold the prerogative of supreme command of a country, and he is surely a rogue and a gangster fond of playing with fire, rather than a politician."
Yesterday, the US president announced further sanctions against banks who do business with the regime.
US Treasury Secretary, Steven Mnuchin, says the measure will curb Pyongyang's military programme:
