Deirdre Griswold of the communist group Workers World Party claimed those in Washington DC are hungry for a war with North Korea.
Ms Griswold told Fox News: “What I want to talk about is what I think is really important to the people of this country – that is that there is a group in Washington that really wants to push for a war.
“The Korean people don’t want it. People here don’t want a war but they don’t know what a war is. They think you just push a button somewhere – that’s not true.”
Mr Carlson hit back and told the North Korea apologist to “hold on”. He admitted there are some people in Washington DC who are thirsty for a war against Kim Jong-un.
But he added: “I guess where I disagree with you is we don’t know what the people of North Korea want because they are not allowed to say what they want.”
In response, Ms Griswold said his comments were “baloney”.
The Fox News host said: “Really? Do they have internet access there? Of they don’t? Ok.”
Ms Griswold said: “They know what is going on in the world. They know perfectly well what’s going on in the world.”
Mr Carlson asked Ms Griswold to highlight how she knew this as he pointed out it is illegal to watch a foreign movie in the hermit nation.
She responded and said Mr Carlson was “making up a lot of stuff”. She said: “The people of North Korea are very aware of what is going on in the world. North Korea has a one hundred percent literacy rate – did you know that?
“I got that figure from the CIA fact book. If you want to check it out. They have universal medical care.
“They are not in some kind of a jail. They are not. They are people who want to get out from underneath the threat of war that the US has posed ever since it invaded their country.”
The Fox News presenter concluded the debate when he pointed out that Ms Griswold “can’t read anything but the propaganda”.
During his New Year’s address, Kim Jong-un warned there is a “nuclear button” on his desk as he threatened the US.
He said: “The entire United States is within range of our nuclear weapons, and a nuclear button is always on my desk. This is reality, not a threat.”
Donald Trump hit back on Twitter. He said: “North Korean Leader Kim Jong Un just stated that the ‘Nuclear Button is on his desk at all times.’
“Will someone from his depleted and food starved regime please inform him that I too have a Nuclear Button, but it is a much bigger & more powerful one than his, and my Button works!”