Homeland Security chief: Kim Jong Un 'knows what he's doing'
"He seems like someone who knows what he's doing," said Kelly to CNN's Jake Tapper on "The Lead."
"Clearly the number one thing in his mind is to remain in power ... He's got to do that by convincing everyone around him ... that he's a strong man and is willing to stand up."
When asked whether he believes that Kim Jong Un is "mentally unbalanced," Kelly conceded that he didn't know.
"I think the only way to decide whether he's insane or not is to lay him down on a couch and have a battalion's worth of psychiatrists talk to him and figure it out," Kelly said.
Kelly also defended Trump's hostile rhetoric on North Korea, telling Tapper that he doesn't think Trump's language is increasing the tension.
"The dictator in North Korea is on his own program," he said. "I think any president that didn't talk about it in stark terms would not be doing his job."
North Korea was reported to have fired a ballistic missile on Friday, one day after the US officials held talks with the South Korean military, and after the US began another stage of its deployment of the controversial Terminal High Altitude Area Defense (THAAD) anti-missile system.
The missile was said to have failed by failing to reach the Sea of Japan, and instead, blew up over land. It was also estimated to have traveled for 25 miles in 15 minutes at an altitude of 44 miles.
"This is Kim giving us the finger," said former US State Department spokesman John Kirby, in a CNN report. "Giving China the finger. Giving the UN the finger. I think timing is absolutely planned and preordained in his mind."