North Korea's state-run media say U.S. President Donald Trump's tweet about having a bigger nuclear button than leader Kim Jong Un's is the "spasm of a lunatic."

Rodong Sinmun, the ruling party newspaper, lashed out at Trump in a commentary on Tuesday that took issue with the U.S. commander in chief's Jan. 3 tweet that "I too have a Nuclear Button, but it is a much bigger & more powerful one than his, and my Button works!"

The tone of Tuesday's article was not uncommon for the North Korean media. But Trump's willingness to respond in kind — he has repeatedly called Kim "little rocket man" — is rare for an American leader and has led to several fiery verbal barrages since he took office nearly a year ago.