North Korea is planning to test a hydrogen bomb in the Pacific Ocean after Donald trump vowed to 'totally destroy' Kim Jong-un's rogue state. 

North Korea's top diplomat said the country planned to test the bomb to fulfill Kim Jong Un's vow to take the 'highest-level of hard-line countermeasure in history' against the US.

The threat comes after US President Donald Trump said he would 'totally destroy' North Korea. At his UN address on Tuesday, president trump warned the North Korean leader that the United States, if threatened, would destroy the country of 26 million people.

Kim Jong-un confirmed his nuclear program was on the 'correct path' this week.

'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 Jong-un said in a statement.  He called Mr Trump 'mentally deranged' and said the US President's comments were 'the most ferocious declaration of war in history'.

'I will surely and definitely tame the mentally deranged US dotard with fire,' Kim said in the rare direct statement, referring to Trump. 

'He has made unprecedented rude nonsense one has never heard from any of his predecessors. 

'A frightened dog barks louder.' 

The letter, issued in the leader's own name, was unusual for North Korea.  'I'd like to advise Trump to exercise prudence in selecting words and to be considerate of whom he speaks to when making a speech in front of the world,' the statement said. 

'After taking office, Trump has rendered the world restless through threats and blackmail against all countries in the world. 

'He is 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.'  

He offered more vitriol for Trump, saying he was 'unfit to hold the prerogative of supreme command of a country, and he would 'pay dearly for his speech calling for totally destroying North Korea. 'Whatever Trump might have expected, he will face results beyond his expectation,' Kim said. 

Foreign Minister Ri Yong Ho said it 'could be the most powerful detonation of an H-bomb in the Pacific', according to South Korea's Yonhap news agency. 

Ri reportedly added: 'We have no idea about what actions could be taken as it will be ordered by leader Kim Jong Un'. 

If North Korea launches the test, it will be considered a major provocation by Washington and its allies.  President Trump signed an executive order on Thursday designed to choke North Korea's economy. 

The president said the new order would cut off sources of revenue that funded North Korea's efforts to develop what he called 'the deadliest weapons known to humankind'. 

The order was designed to dissuade Pyongyang from pursuing its nuclear missile program. 

Pyongyang is the capital city of North Korea.