President Trump tweeted on Sunday that Secretary of State Rex Tillerson is “wasting his time” trying to negotiate with North Korea and the rogue nuclear nation’s leader, Kim Jong Un.

“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. “Save your energy Rex, we’ll do what has to be done!”

I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man…

Donald J. Trump (@realDonaldTrump) October 1, 2017 [restrict]

…Save your energy Rex, we’ll do what has to be done!

— Donald J. Trump (@realDonaldTrump) October 1, 2017

Trump’s tweets appeared to undercut the work of his chief diplomat.

At a press conference in Beijing on Saturday, Tillerson told reporters that the United States has established direct lines of communications to Pyongyang in the hopes of coming to “a peaceful resolution” in North Korea.

“We’ve made it clear that we hope to resolve this through talks,” Tillerson said. “I think the most immediate action that we need is to calm things down. They’re a little overheated right now, and I think we need to calm them down first.”

In an address to the U.N. General Assembly last month, Trump warned that if the United States is forced to defend itself from Pyongyang’s nuclear provocations, “we will have no choice but to totally destroy North Korea.”

“Rocket Man is on a suicide mission for himself and for his regime,” the president said.

The speech drew strong rebukes from critics who said the president used the United Nations “as a stage to threaten war.”

Trump’s Sunday morning Twitter diplomacy sparked speculation about Tillerson’s job security.

Richard Haass, president of the Council on Foreign Relations, who once served as an adviser to former Secretary of State Colin Powell, was among many foreign policy experts suggesting Tillerson should resign.

Diplomacy not a favor we dispense but a critical national security tool for ourselves. Potus truly misguided here-& SecState should resign. — Richard N. Haass (@RichardHaass) October 1, 2017

Isn’t Rex going to resign sooner rather than later?

— Bill Kristol (@BillKristol) October 1, 2017

Trump just took out Tillerson’s knee caps. Why wouldn’t Tillerson just resign? =— Eddie S. Glaude Jr. (@esglaude) October 1, 2017

In light of these tweets undercutting SecState, reupping my article on why Tillerson has failed & should quit: — Max Boot (@MaxBoot) October 1, 2017

really hard to see what’s in it for Rex Tillerson to be Sec of State — he is no good at it, his boss disgraces him, every day diminishes him. — Philip Gourevitch (@PGourevitch) October 1, 2017

“Save your energy Rex.”

Humilating for Tillerson, but worse, renders him useless.

He’ll resign, today or after a brief face-saving interval. — Dan Shapiro (@DanielBShapiro) October 1, 2017

President Trump spectacularly shot down SecState Tillerson after important Beijing talks. How long can this last? — Carl Bildt (@carlbildt) October 1, 2017

Tillerson has lately taken to calling Jared & Ivanka “the royal family.” He’s not expecting to be there long. — ian bremmer (@ianbremmer) October 1, 2017 [/restrict]