Every path for North Korea leads to "catastrophe" if Kim Jong-un is toppled, according to a journalist who reported from the country undercover.

Opening up North Korean society is "a completely bleak problem" because citizens "have been deprived of any tools that they need, education, information, sharing tools", Suki Kim said.

Ms Kim authored the book Without You, There Is No Us after working as an English teacher at the Pyongyang University of Science and Technology, and smuggling notes out of the country.

"It’s not a system that they can moderate. The Great Leader can’t be moderated. You can’t be a little bit less god. The Great Leader system has to break. But it’s impossible to imagine," she told The Intercept.

She added: "[Military] intervention is not going to work because it’s a nuclear power. I guess it has to happen in pouring information into North Korea in whatever capacity.

"But then the population are abused victims of a cult ideology. Even if the Great Leader is gone, another form of dictatorship will take its place. Every path is a catastrophe. I’d love to offer up solutions but everything leads to a dead end."

The news comes as the crisis on the Korean peninsula threatens to worsen even further, with reports from South Korea on Tuesday that its neighbour was moving a rocket, apparently an intercontinental ballistic missile, towards its west coast.

The Kim regime had conducted its sixth nuclear test on Sunday, detonating what it claimed was a thermonuclear device measured as being several times more powerful than its previous effort.

Ms Kim warned: "North Korea will never give up its nuclear weapons. Never."

Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Show all 6 1 /6 Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb Photos released by North Korea show Kim Jong-un talking to subordinates next to a device thought to be the new thermonuclear weapon. There is no way of independently verifying the pictures STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb North Korea claims it has successfully tested an advanced hydrogen bomb which could be loaded onto an intercontinental ballistic missile AFP/Getty Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A diagram on the wall behind Mr Kim shows a bomb mounted inside a cone STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb North Korean leader Kim Jong-Un (C) attending a photo session with participants of the fourth conference of active secretaries of primary organisations of the youth league of the Korean People's Army (KPA) in Pyongyang STR/AFP/Getty Images Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A new stamp issued in commemoration of the successful second test launch of the "Hwasong-14" intercontinental ballistic missile KCNA via Reuters Kim Jong-un inspects weapon North Korea says is powerful hydrogen bomb A new stamp issued in commemoration of the successful second test launch of the "Hwasong-14" intercontinental ballistic missile KCNA via Reuters

It echoed the claims of the North's highest-ranking defector, Thae Yong-ho. Mr Thae was the deputy ambassador in London and defected to the South last year.

He said the Kim regime was determined to complete its nuclear weapons development by the end of 2017, and that it would not relinquish them "even if the country is offered $1 trillion or $10 trillion in return".