SEOUL (Reuters) - North Korea s leader Kim Jong Un said on Friday the North will consider the  highest level of hard-line countermeasure in history  against the United States in response to U.S. President Donald Trump s threat to destroy the North. Calling Trump  mentally deranged  and his comments  the most ferocious declaration of a war in history,  Kim said his U.N. speech on Tuesday confirmed Pyongyang s nuclear program has been  the correct path .  His remarks ... have convinced me, rather than frightening or stopping me, that the path I chose is correct and that it is the one I have to follow to the last,  Kim said in the statement carried by the North s official KCNA news agency, promising to make Trump  pay dearly for his speech . Trump had warned the North Korean leader in his U.N. address on Tuesday that the United States, if threatened, would  totally destroy  the country of 26 million people and mocked Kim as a  rocket man  on a suicide mission. It was the U.S. president s most direct reference to military action so far against the North, which conducted its sixth and largest nuclear test on Sept. 3. In addition to the nuclear test, North Korea has launched dozens of missiles since Kim came to power in 2011. Two recent ballistic missiles flew over Japan as Pyongyang advanced toward its goal of creating nuclear warhead-tipped missiles that can hit the United States.     Kim said Trump would face  results beyond his expectation,  without specifying what action North Korea would take next.  I will surely and definitely tame the mentally deranged U.S. dotard with fire,  Kim said in the rare direct statement, referring to Trump. He offered more vitriol for Trump, saying he was  unfit to hold the prerogative of supreme command of a country, and he is surely a rogue and a gangster fond of playing with fire, rather than a politician.  A day after Trump s address, North Korea s Foreign Minister Ri Yong Ho had likened Trump to a  barking dog,  saying his comments were no threat to the North. Kim took a page out of Ri s book on Friday, saying  a frightened dog barks louder .  Now that Trump has denied the existence of and insulted me and my country in front of the eyes of the world.., we will consider with seriousness exercising of a corresponding, highest level of hard-line countermeasure in history,  Kim said. 