The White House on Wednesday defended Donald Trump¡¯s tweet about the size of his nuclear button, saying Americans should be concerned about the North Korean leader¡¯s mental fitness, not their president¡¯s.

On Tuesday, Trump responded to a New Year¡¯s Day speech in which North Korean leader Kim Jong Un warned he had a nuclear button on his desk by saying that his nuclear button ¡°is a much bigger & more powerful one than his, and my Button works!¡±

The tweet provoked strong criticism, especially from Trump¡¯s Democratic opponents, and former Vice President Joe Biden called it dangerously cavalier.