The top U.S. nuclear commander said he would decline President Trump if he ordered an “illegal” nuclear launch.

Air Force Gen. John Hyten, commander of the U.S. Strategic Command, made the remarks to an audience at the Halifax International Security Forum in Halifax, Nova Scotia, on Saturday.

Hyten was asked if he has given a lot of thought to what he would say if Trump ordered a nuclear strike, especially if he considers it unlawful.

"I think some people think we're stupid. We're not stupid people. We think about these things a lot. When you have this responsibility, how do you not think about it?" Hyten said in response.

Hyten oversees the U.S. nuclear arsenal as head of STRATCOM.

"I provide advice to the president, he will tell me what to do," Hyten explained. "And if it's illegal, guess what's going to happen? I'm going to say, 'Mr. President, that's illegal.' And guess what he's going to do? He's going to say, 'What would be legal?' And we'll come up options, with a mix of capabilities to respond to whatever the situation is, and that's the way it works. It's not that complicated."

Hyten added that if Trump were to “execute an unlawful order., you will go to jail," he said. “You could go to jail for the rest of your life."

Hyten’s comments come as Trump has ratcheted up his rhetoric against North Korea. He has said in different scenarios that he wants to unleash “fire and fury” and “totally destroy” North Korea, which has been developing its missile and nuclear weapons programs and consistently threatens countries like the U.S.

Hyten said the U.S. is ready to respond to “any event that comes out of North Korea” and an unpredictable leader in Kim Jong Un. But that “the element of deterrence” has to be clear.

"President Trump by himself can't change the behavior of Kim Jong Un," Hyten said. "But President Trump can create the conditions that the international community can reach out in different ways where we can work with the Republic of Korea, where we can work with our neighbors in the region."