President Trump tweeted Sunday morning that Secretary of State Rex Tillerson was wasting his time trying to negotiate with North Korean 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,” he tweeted. “Save your energy Rex, we’ll do what has to be done!”

Trump’s tweets come after Tillerson said Saturday in Beijing that the U.S. had several channels they were using to communicate with North Korea over its nuclear and ballistic missile tests.

It was the first time a Trump administration official had admitted they were in open communication with the rogue regime.

“We are probing, so stay tuned,” Tillerson said, according to the New York Times. “We ask, ‘Would you like to talk?’ We have lines of communications to Pyongyang — we’re not in a dark situation, a blackout … . We have a couple, three channels open to Pyongyang.”

“We can talk to them,” he said. “We do talk to them.” He said those channels did not go through China. “Directly … . We have our own channels.”

The Trump administration is pursuing a policy of working with the United Nations, China and taking its own measures to increase economic pressure on North Korea and its allies through sanctions, to drive it to the negotiating table with the goal of denuclearization.

Trump’s tweets suggest he is opposed to trying to negotiate with Kim Jong-Un — who he has dubbed “Little Rocket Man.” Former acting CIA Director Michael Morrell believes Washington should give up on getting North Korea to give up its weapons, and work on deterring it from ever using those weapons.

Trump could also be acting as if he is opposed to Tillerson’s efforts, in a good cop, bad cop routine. It is also possible he feels Tillerson erred by admitting publicly the Trump administration wanted to talk. Japanese Prime Minister Shinzo Abe is opposed to talking yet.

Hours after Tillerson left China, State Department Press Secretary Heather Nauert said North Korean officials had shown no indication they were “interested or ready” for talks.

“Despite assurances that the United States is not interested in promoting the collapse of the current regime” or sending American forces into the country, “North Korean officials have shown no indication that they are interested in or ready for talks regarding denuclearization,” she said.

Trump has said himself during the 2016 presidential campaign that he would be open to negotiating with Kim directly.