US president Donald Trump said on Sunday he told the top US diplomat not to waste his time trying to negotiate with North Korean leader Kim Jong Un, whom he has dubbed "Rocket Man."
"I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man," Mr Trump wrote on Twitter.
His comments come a day after Mr Tillerson disclosed the US was directly communicating with North Korea on its nuclear and missile programmes but that Pyongyang had shown no interest in dialogue.
...Save your energy Rex, we'll do what has to be done!
— Donald J. Trump (@realDonaldTrump) October 1, 2017
“Save your energy Rex, we’ll do what has to be done!” Mr Trump said.