President Trump tweeted Sunday that Rex Tillerson is "wasting his time trying to negotiate with" Kim Jong-un.br br President Trump tweeted Sunday morning that Secretary of State Rex Tillerson is "wasting his time" on North Korea, while referring to the nation's leader Kim Jong-un as "Little Rocket Man."brbr"I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man," Trump tweeteda. "Save your energy Rex, we'll do what has to be done!"brThe president's tweet comes after Tillerson told reporters on Saturday that the U.S. is in direct communication with North Korea.br"Tillerson, on a one-day trip to Beijing, left the door open to negotiations," Bloomberg reporteda. "That’s a stance that runs counter to what others in the U.S. administration -- including President Donald Trump -- have said."brAmid the ratcheting of tensions over North Korea's continued missile testing, Trump has threatened to "totally destroy" the reclusive Asian country.br"Rocket Man is on a suicide mission for himself," Trump said during his recent United Nations address and then tweeted days later, "Just heard Foreign Minister of North Korea speak at U.N. If he echoes thoughts of Little Rocket Man, they won't be around much longer!"brMeanwhile, Kim called Trump a “mentally deranged U.S. dotard," as part of a statement released in September.