John Heilemann, a national affairs analyst for MSNBC, said Wednesday that President TrumpDonald John TrumpFive takeaways from Cruz, O'Rourke's debate showdown Arpaio files libel suit against New York Times IMF's Christine Lagarde delays trip to Middle East MORE's claim that the U.S. nuclear arsenal is "much bigger" than that of North Korea makes him look "demented and deranged."

"He is not merely being cavalier with a threat about nuclear war," Heilemann said on "Morning Joe." "He's being cavalier in a way that makes him seem demented and deranged, and makes none of our serious allies or adversaries around the world think that he's a serious person talking in this way about the most serious threat that the world ever faces."

Heilemann's comments came after Trump responded on Tuesday to North Korean leader Kim Jong Un's claim that he has a nuclear launch button on his desk by tweeting that the U.S. launch button was "more powerful" and assuring that it is functional.

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The president's tweet appeared to dismiss Kim's assertion that the international community would have to accept North Korea as a nuclear-armed state and raised once again the prospect of a confrontation with Pyongyang.

The possibility of a dialogue between North Korea and South Korea, a U.S. ally, got a boost this week, after officials in both countries suggested potential talks ahead of the 2018 Winter Olympics, which are set to begin in Pyeongchang, South Korea, in February.

The two countries reopened a hotline on Wednesday, reestablishing a key line of communication between Seoul and Pyongyang.