North Korea faces destruction if it continues to threaten the US and its allies, according to one of Donald Trump’s most senior diplomats, while the president unveiled the dismissive new nickname of Rocket Man for the country’s erratic ruler.

With world leaders gathering in New York for the United Nations General Assembly, when North Korea’s nuclear programme is expected to dominate, senior administration figures said time was running out for a diplomatic solution.

Nikki Haley, the US ambassador to the UN, said North Korea was starting to feel the pinch of sanctions but added that she would be happy to turn the matter over to the military.

“We all know that if North Korea continues with this reckless behaviour and if the United States has to defend itself or its allies in any way, North Korea will be destroyed,” she said.