President Donald Trump said Sunday he has told his top diplomat he is wasting his time trying to negotiate a diplomatic solution with North Korea.
"Save your energy Rex, we'll do what has to be done!" Trump wrote on Twitter, referring to Secretary of State Rex Tillerson.
Trump did not elaborate, but threatened to "totally destroy" North Korea last month during his first address to the United Nations.
While in China on Saturday, Tillerson acknowledged the U.S. has diplomatic channels to North Korea, a country with which it has no formal relations. He said the U.S. is seeking to determine if Pyongyang would be willing to participate in talks.
The State Department later added that North Korea has "shown no indication" it is willing to take part in negotiations on the long-sought de-nucearization of the Korean Peninsula.
"I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man," Trump said, using his nickname for North Korean leader Kim Jong-un.
North Korea faces strong sanctions by the United States and firm condemnation from the international community in the wake of repeated missile launches and nuclear tests.
Pyongyang's sixth nuclear test Sept. 3 led to the adoption of the ninth UN Security Council resolution since 2006, which further tightened international sanctions on the country.
By Michael Hernandez