Donald Trump Calls Kim Jong-un 'Short and Fat' in Response to Being Called Old

Donald Trump just took the high road in a war of words with the leader of North Korea ... just kidding -- he called him short and fat.

The Prez responded to Kim Jong-un calling him old and threatening nuclear war by dishing out an insult Saturday night (Sunday morning for Trump, who's currently in Vietnam), posting on Twitter ... "Why would Kim Jong-un insult me by calling me 'old,' when I would NEVER call him 'short and fat?'"

Trump went on, sarcastically claiming he's tried hard to be the North Korean leader's friend and saying "maybe someday that will happen!"

Trump's jab appears to be his response to Jong-un referring to the President as a "dotard" who "begged for nuclear war" during his tour of Asia ... which he's still on. Or, it could be from North Korea's state-run media calling Trump a "lunatic old man."