Donald Trump, the President of the US, has told the man in charge of his country's negotiations with North Korea that they are "a waste of time" in his latest provocative tweet about the secretive state with potential nuclear weapons.
He said that he had told US secretary of state Rex Tillerson that "he is wasting his time with Little Rocket Man" the nickname he has given North Korean leader Kim Jong Un.
In a second tweet he said: "save your energy Rex, we'll do what has to be done."
Previous tweets by Trump elicited an unprecedented response from the dictator directed straight to the President in which he called him a dotard.
And the latest tweets are in stark contrast to Tillerson's own stance on talks and his efforts to facilitate them. He has said over the weekend that the US is in "direct contact" with Pyongang on a trip to China.