It's an extraordinary and direct rebuke from Kim Jong Un.
The North Korean leader is calling U-S President Donald Trump ''deranged'' and says he will ''pay dearly'' for his threats, a possible indication of more powerful weapons tests on the horizon.
Hours later, North Korea's foreign minister reportedly said his country may be planning to test a hydrogen bomb in the Pacific Ocean to fulfil Kim's vow to take the ''highest-level'' action against the United States.
Kim, in his statement, says Trump is ''unfit to hold the prerogative of supreme command of a country.''
He also described the U-S president as ''a rogue and a gangster fond of playing with fire.''