Stephen Colbert thinks President Donald Trump "isn't fit to sit in a White Castle, let alone a White House" -- but that doesn't mean North Korean leader Kim Jong-un can gang up on him.

In a teaser for Friday night's episode of Late Night, Colbert had harsh words for Kim and North Korean foreign minister Ri Yong Ho, who compared Trump to a barking dog while visiting New York for the United Nations General Assembly.

“Pretty sick burn on our president, to which I have to say, knock it off, North Korea,” Colbert said of Ri's comments. “You are not allowed to insult our leader like that."

"Sure, I’ve had my problems with President Trump, such as everything he has said and done," he continued, "but I’m not going to stand here, as an American, and let somebody from another country talk smack about our president.”

Colbert was particularly affronted by Ri's presence in New York for the G.A. while making his comments.

"You come to my house and insult my president," he said, "who granted, I think isn’t fit to sit in a White Castle, let alone a White House."

Watch the segment below, via Late Night and CBS.