So what is the threat to the UK – and how could Britain react?
In July 2016, Theresa May warned that the threat of a nuclear attack had “increased”.
In a speech trying to make the case for keeping the UK’s nuclear deterrent, the PM said: “The nuclear threat has not gone away; if anything, it has increased.”
On the same day, Michael Fallon, the Defence Secretary, highlighted the threat from Kim Jong-un’s rogue regime in particular.
“There are already some 17,000 nuclear weapons in the world today,” he wrote in the Telegraph. “Rogue states like North Korea are testing them. Terrorist groups are trying to get hold of them.”
According to a former US Navy SEAL, Britain and the US have already devised three different plans for how to take out the entire government of North Korea.
In an interview with The Mirror, former SEAL Brandon Webb said elite forces were already being trained for a scenario where they are ordered to take out Kim Jong-un in an operation not dissimilar from the assassination of Osama Bin Laden in 2011.
According to Webb, the operation would involve parachuting special forces operatives into the secretive hermit state from across the border of South Korea, where they would reportedly avoid detection.
The 43 year old said: ‘I think it would be very easy for the UK or the US to, if they wanted, swiftly take out the entire North Korean leadership. Very quickly, with a special operations unit.
‘The intelligence capability and the special ops capability we have today is incredible. Most people have no idea really how effective the US and the UK are at conducting these missions.’
Where are we now?
President Trump yesterday claimed that the US was prepared to attack North Korea with “fire and fury like the world has never seen”.
In response, North Korean state news agency KCNA claimed that the possibility of a pre-emptive nuclear strike on Guam was being considered.
Kim Jong-un has repeatedly threatened a strike on America, but there is no suggestion that he plans to attack major European cities.
It is also thought that any warheads will lack the capability to reach Europe – with Hawaii and Alaska instead thought to be likely targets in the event of a nuclear attack.
However, a leading scientist has warned that the rockets could potentially reach London.
David Wright from the Union of Concerned Scientists told MailOnline: ‘The missile flown on a standard trajectory the missile would have a range 10,400 km (6,500 miles), not taking into account the Earth’s rotation.’