Watch: Boris Johnson warns of 'catastrophe' if Kim Jong Un realises nuclear ambition
Boris Johnson has warned the situation in North Korea is "very, very serious" after referring to Donald Trump's mockery of "Rocket Man" Kim Jong Un.
The Foreign Secretary said the world faced a catastrophe if North Korea - a "rogue nation" - was able to mount a nuclear warhead on an intercontinental ballistic missile (ICBM).
He repeated his call for China to put more pressure on the Pyongyang regime as he urged a diplomatic solution to the crisis.
In a social media video message recorded at the United Nations in New York, Mr Johnson referred to Mr Trump's debut speech at the annual gathering of world leaders.
Mr Trump told the UN "Rocket Man is on a suicide mission for himself and his regime" and added that if the US was "forced to defend itself or its allies, we will have no choice but to totally destroy North Korea".
Mr Johnson said: "You heard the President of the United States' speech about Rocket Man - Elton John getting a place in Donald Trump's speeches.
"Of course it's very, very serious. The world faces a catastrophe that it hasn't seen before, that is a rogue nation being able to use an ICBM equipped with a thermonuclear hydrogen warhead.
"That is very, very dangerous, something we have got to stop.
"The key to it, we think, is to work together with all our friends and partners here in the UN, get the Chinese to put more economic pressure on Pyongyang."
At the summit, Mr Johnson met Chinese foreign minister Wang Yi and urged him to keep up the pressure on North Korea.
The British Foreign Secretary told the Guardian: "No one in their right minds wants to see the US driven to use its military options - I do not see any good military options - and that is why all the pressure has to be on the Chinese to tighten the sanctions on oil.
"That is the jugular of the North Korean economy.
"China has been responding in a mature way, and they say if you go in too hard you will cause a catastrophe and mass migrations. Before that happens it may be possible to bring Kim Jong Un to the table."
Mr Johnson also met Japanese foreign minister Taro Kono and reiterated the UK's solidarity with Japan over the threat it faces from Kim's regime.
