Trump Breaks With His Secretary of State, Says 'Wasting His Time' on North Korea Diplomacy

'Save your energy Rex, we'll do what has to be done! Trump tweeted

Rocket Man Kim Jong-il, on July 2006 Economist cover

U.S. President Donald Trump said on Sunday he told the top U.S. 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," Trump wrote on Twitter a day after Tillerson disclosed the United States was directly communicating with North Korea on its nuclear and missile programs but that Pyongyang had shown no interest in dialogue.

"Save your energy Rex, we'll do what has to be done!" Trump said. 

The U.S. president did not elaborate, but he told the United Nations last month that if the U.S. is "forced to defend itself or its allies, we will have no choice but to totally destroy North Korea."

Tillerson — while in China — said Saturday the U.S. is maintaining direct channels of communications with North Korea and probing the North's willingness to talk.

Trump says he's told Tillerson that "he's wasting his time trying to negotiate with Little Rocket Man."