Secretary of State Rex Tillerson addressed concerns that President Donald Trump had undercut him in several interviews Sunday.

At the beginning of October Trump tweeted about North Korea, and said that Tillerson was wasting his time on diplomacy with North Korea.

“I told Rex Tillerson, our wonderful Secretary of State, that he is wasting his time trying to negotiate with Little Rocket Man,” said Trump on Twitter, referring to North Korea’s leader Kin Jong Un. “Save your energy Rex, we'll do what has to be done!”

The move was seen as a direct challenge to Tillerson’s job. Tennessee Republican Sen. Bob Corker this week also accused the president of “castrating” Tillerson, undercutting his role.

“You cannot publicly castrate your own secretary of state,” said Corker who chairs the Foreign Relations Committee to the Washington Post Friday.

Corker has been highly critical of the president since deciding not to seek reelection, but had high praise for Tillerson. Corker worries that Trump is limiting the U.S. options for dealing with North Korea.

Tillerson responded to Corker on CNN Sunday.

“I checked, I’m fully intact,” said Tillerson.

Tillerson also defended his diplomatic work with North Korea.

“Those diplomatic efforts will continue until the first bomb drops,” said Tillerson.

The U.S. and North Korea have no official diplomatic relations, but communicate through back channels. Tension between the two nations has been especially high this year. North Korea has been aggressively advancing its nuclear and missile capabilities and showcasing it to the world through provocative tests. North Korea also released a U.S. college student who had been in captivity, but the student was in a mysterious coma and brain damaged and died shortly after returning home.

Trump has used an especially aggressive and threatening rhetoric towards the country, often taking it upon himself to respond to North Korea’s aggression.

Tillerson defended his relevance on CBS, Sunday.

“The president wants to know what I think,” said Tillerson. “I have complete freedom to express my views to the president. And he listens to those views.”

Tillerson was also asked about an NBC News report that alleged he called Trump a “moron” over the summer. Tillerson evaded the question.

“I'm not going to deal with that kind of petty stuff,” said Tillerson to CNN. “I mean, this is a town that seems to relish in gossip, rumor and innuendo. And they feed on it. They feed on it in a very destructive way. I don't work that way and I don't feel that way.”