North Korean leader Kim Jong Un delivered a scathing rebuke Friday of U.S. President Donald Trump, calling him "mentally deranged" and vowing to make him "pay dearly" for threatening to "totally destroy" his country — a possible allusion to further weapons tests as the country's top diplomat hinted that a hydrogen bomb test may be carried out over the Pacific Ocean.

Kim said in a statement carried by state media that Trump "has rendered the world restless through threats and blackmail against all countries in the world," calling him "unfit to hold the prerogative of supreme command of a country" and referring to him as "a rogue and a gangster fond of playing with fire."

Kim's statement, unusual in that it was written in the first person and was apparently his first direct appeal to the world, according to South Korea's Unification Ministry, came after Trump, in his inaugural speech before the U.N. General Assembly on Tuesday, laid into the regime and Kim himself.