North Korea will never completely give up its nuclear weapons, a top defector said ahead of leader Kim Jong Un's landmark summit with US President Donald Trump next month.
The current whirlwind of diplomacy and negotiations will not end with "a sincere and complete disarmament" but with "a reduced North Korean nuclear threat", said Thae Yong-ho, who fled his post as the North's deputy ambassador to Britain in August 2016.
"In the end, North Korea will remain 'a nuclear power packaged as a non-nuclear state'," Thae told the South's Newsis news agency.
His remarks come ahead of an unprecedented summit between Kim and Trump in Singapore on June 12 where North Korea's nuclear and missile programmes are expected to dominate the agenda.
North and South Korea affirmed their commitment to the goal of denuclearisation of the peninsula at summit last month, and Pyongyang announced at the weekend it will destroy its only known nuclear test site next week.
But it has not made public what concessions it is offering.
Washington is seeking the "complete, verifiable and irreversible denuclearisation (CVID)" of the North and stresses that verification will be key.
Pyongyang has said it does not need nuclear weapons if the security of its regime is guaranteed.
But Thae, one of the highest ranking officials to have defected in recent years, said: "North Korea will argue that the process of nuclear disarmament will lead to the collapse of North Korea and oppose CVID."
The North wanted to ensure Kim's "absolute power" and its model of hereditary succession, he added, and would oppose intrusive inspections as they "would be viewed as a process of breaking down Kim Jong Un's absolute power in front of the eyes of ordinary North Koreans and elites".
At a party meeting last month when Kim proclaimed the development of the North's nuclear force complete and promised no more nuclear or missile tests, he called its arsenal "a powerful treasured sword for defending peace".
"Giving it up soon after Kim Jong Un himself labelled it the 'treasured sword for defending peace' and a firm guarantee for the future? It can never happen," Thae said.
In his memoir that hit shelves Monday, Thae added: "More people should realise that North Korea is desperately clinging to its nuclear programme more than anything."
Tensions on and around the peninsula had been mounting for years as Pyongyang's nuclear and ballistic missile programmes saw it subjected to multiple rounds of increasingly strict sanctions by the UN Security Council, the US, EU, South Korea and others.
Trump last year threatened the North with "fire and fury".
But since the Winter Olympics in the South, Pyongyang and Washington have agreed to the unprecedented Singapore meeting.
Kim has also twice visited China after not paying his respects to President Xi Jinping in the six years since he inherited power from his father, and met the South's President Moon Jae-in in the Demilitarized Zone that divides their countries.
North Korea's sudden change in attitude was probably driven by the mounting international sanctions imposed over its weapons programmes that had begun to take a toll on the livelihoods of ordinary citizens, Thae said.
As of last year the UN Security Council sanctions included measures on sectors such as coal, fish, textiles and overseas workers.
"North Korea did not foresee the destructive power of these sanctions," Thae told the interview. "These sanctions are threatening the livelihoods of millions of North Koreans at the root."
But Pyongyang had a long history of making overtures that ultimately came to nothing, he warned.
"North Korea's diplomacy has always been a repeat of hardline and appeasement," Thae said.
"It is North Korea's diplomatic tactic to push the situation to extreme confrontation and suddenly send peace gestures."
The fact is, North Korea's latest and largest underground nuclear test last year was powerful enough to move a mountain, say scientists who found that the bomb was 10 times stronger than the one dropped by the United States on Hiroshima during World War II.
Researchers, including those from Nanyang Technological University in Singapore and University of California, Berkeley in the US, showed how the explosion altered the mountain above the detonation.
The nuclear test on September 3, 2017 took place under Mt Mantap at the Punggye-ri nuclear test site in the country’s north, rocking the area like a 5.2-magnitude earthquake, according to the study published in the journal Science.
What an impact!
Based on seismic recordings from global and regional networks, and before-and-after radar measurements of the ground surface from Germany’s TerraSAR-X and Japan’s ALOS-2 radar imaging satellites, researchers showed that the underground nuclear blast pushed the surface of Mt Mantap outward by as much as 3.5 metres and left the mountain about 0.5 metres shorter.
By modelling the event on a computer, they were able to pinpoint the location of the explosion and its depth, 400-600 metres below the peak.
They also located more precisely another seismic event, or aftershock, that occurred 8.5 minutes after the nuclear explosion, putting it some 700 metres south of the bomb blast.
This is about halfway between the site of the nuclear detonation and an access tunnel entrance and may have been caused by the collapse of part of the tunnel or of a cavity remaining from a previous nuclear explosion.
“This is the first time the complete three-dimensional surface displacements associated with an underground nuclear test were imaged and presented to the public,” said Teng Wang of the Earth Observatory of Singapore at Nanyang Technological University.
Putting all of this together, the researchers estimate that the nuclear test, North Korea’s sixth and the fifth inside Mt. Mantap, had a yield between 120 and 300 kilotons, about 10 times the strength of the bomb dropped by the US on Hiroshima during World War II.
That makes it either a small hydrogen, or fusion, bomb or a large atomic, or fission, bomb.
The explosion occurred more than a 450 metres below the summit of Mt Mantap, vaporising granite rock within a cavity about 50 metres across — the size of a football stadium — and damaging a volume of rock about 300 metres across.
The blast likely raised the mountain two metres and pushed it outward up to 3-4 metres, though within minutes, hours or days the rock above the cavity collapsed to form a depression.
Eight and a half minutes after the bomb blast, a nearby underground cavity collapsed, producing the 4.5-magnitude aftershock with the characteristics of an implosion.
Subsequently, a much larger volume of fractured rock, perhaps 1-2 kilometres across, compacted, causing the mountain to subside to about 0.5 metres lower than before the blast.
While it is possible to discriminate explosions from natural earthquakes using seismic waveforms, the uncertainty can be large, researchers have said.
Explosions often trigger nearby earthquake faults or other natural rock movements that make the seismic signals look earthquake-like, confusing the analysis.