NEWS ANALYSIS

The factors that drive North Korean leader Kim Jong Un's nuclear arsenal

North Korea says its carried out its sixth nuclear test, this time using a newly built hydrogen bomb. The blast is the most powerful to date and caused a significant earthquake.

TOKYO (NYTIMES) - What does North Korean leader Kim Jong Un want?

That remains far harder to answer than the technical questions about Mr Kim's bombs and the reach of his missiles that have preoccupied American, Japanese and South Korean intelligence officials for years.

After North Korea's underground test on Sunday (Sept 3), more is now known about the power of his nuclear arsenal, even if mystery remains about the veracity of the North's claim that it detonated a hydrogen bomb.

Yet six years after Mr Kim took power and began executing those who challenged his rule, there is no issue that more confounds analysts than the motives of a 33-year-old dictator whose every move seems one part canny strategy, one part self-preservation, and one part nuclear narcissism.

DEFENSIVE MOVE

The conventional wisdom has always been that Mr Kim, like his father and grandfather before him, is mostly motivated by a deep desire to preserve the family business - a small country that is an improbable, walled-off survivor of Cold War.

But inside the Trump administration, many have begun to question the long-held assumption that Mr Kim's nuclear buildup is essentially defensive, an effort to keep the United States and its allies from finding the right moment to try to overthrow him.

Mr Kim's real goal may be blackmail, they argue - the sort that would be possible as soon as North Korea can put Los Angeles or Chicago or New York at risk.

It may be splitting the US away from two allies - Japan and South Korea - who wonder whether the US would really protect them, and half-expect US President Donald Trump to make good on his campaign threat that he might pull American troops from the Pacific.

Or it may be about making Mr Kim a power broker, a man Mr Trump and Chinese President Xi Jinping - leaders of the two superpowers Mr Kim is fixated on - must treat as an equal.

Maybe it is about all three.

Very few people outside of North Korea have met Mr Kim, including his supposed protectors, the Chinese.

Defectors periodically appear in London or Seoul, and offer insights, but few are true insiders. Documents revealed by Edward Snowden show that American intelligence agencies broke into the computer systems of the Reconnaissance General Bureau - the North Korean CIA - but they learnt more about operations than intentions.

"Anybody who tells you what North Korea wants is lying, or they're guessing," said Mr Jon Wolfsthal, a scholar in the nuclear policy programme at the Carnegie Endowment for International Peace and former senior director for arms control and non-proliferation in the National Security Council under former president Barack Obama.

"We don't know what Kim Jong Un has for breakfast, so how can we know what his real end game is? We just don't have great intelligence into his personal thinking."

In public statements, the country has made clear that it wants to be accepted as a full member of the international community and that it wants to develop its economy alongside its nuclear programme.

It has also maintained as a longtime goal the desire to reunify with South Korea - on the North's terms. Although Mr Kim makes repeated bellicose threats against the US and South Korea, such statements are always conditioned on the Americans or South Koreans continuing their "hostile policy'' against the North.

But none of that explains the pace at which Mr Kim - more technically savvy and more brutal than his father - has raced in the past year to develop an arsenal of nuclear weapons that can hit multiple targets in the continental US.

"He wants to demonstrate his ability to put a US city at risk of nuclear attack," Mr Michael Morell, the former deputy director of the CIA, said on "Face the Nation" on CBS on Sunday. "That is where he is driving."

He has nearly achieved that goal.

The most commonly heard explanation is that Mr Kim believes that once he can hit Los Angeles, or maybe New York and Washington, the US would never risk doing to him what it helped do to Moammar Gadhafi, the now-deceased Libyan leader.

Mr Gadhafi gave up all the elements of his nascent nuclear weapons programme in 2003, in return for promises of economic integration with the West. That never fully materialised. And as soon as there was an uprising against him, the US, European allies and some Arab states bombed him. He was found by rebel forces and executed.

WITHDRAW SANCTIONS

But perhaps more than a self-preservation strategy is at work here. Mr Kim, some Trump administration advisers and outside experts believe, thinks he may be able to force the US to withdraw sanctions and pull back its troops from South Korea, where they are a perennial irritant to Pyongyang.

Where analysts diverge is what he might do if the US really did withdraw some or all of its forces, as former chief strategist Stephen Bannon suggested that Washington consider doing. One fear is that it could use its nuclear arsenal as a shield for a military invasion of South Korea in an attempt to reunify the peninsula by force.

The worry, say those who fear the North is considering that option, is that its ability to strike the US with nuclear missiles could undermine Americans' ability to guarantee that it would protect South Korea, as well as Japan, from attack.

"If the Americans face a choice between San Francisco and Seoul, they will choose San Francisco," said Mr Andrei Lankov, a North Korea expert at Kookmin University in Seoul.

Based on that calculation, North Korea "can provoke a conflict in South Korea and then they can just basically put an ultimatum to the United States telling the Americans that if they get involved, they are going to basically get a North Korean retaliation strike", Mr Lankov said.

Such a conflict would be catastrophic for Asia, and could lead to the loss of hundreds of thousands of lives. But it would also undercut every assurance the US has made to other allies, from Nato to New Zealand, about coming to their defence.

The probability that the North intends to use force to reunify the peninsula, Mr Lankov said, is "low, but real". It is also one of the regime's stated goals, though one that - in the absence of nuclear weapons - it has never had a realistic hope of achieving. Many believe it is a fantasy, with or without a nuclear arsenal.

"North Korea does not have the power to carry out an all-out war that could last a long time for unification by force," said senior researcher Cho Han Bum, a senior researcher at the Korea Institute for National Unification, a South Korean government-funded think tank. "There is no way North Korea, while suffering from food shortages, can liberate South Koreans by force. (Mr Kim) has no intention of putting his words into action," said Mr Cho.

He may well be right, but given the miserable track record of anticipating Mr Kim's intentions, neither American nor South Korean leaders seem eager to make that assumption. One senior Trump administration official noted that in 1950, everyone assumed the North was too weak to invade the South, and were wrong.

"It is important to take Pyongyang's threat seriously," said Mr Mo Jongryn, dean of the graduate school of international studies at Yonsei University in Seoul.

CYBER PROGRAMME

There is another, less dramatic interpretation of Mr Kim's intentions. The combination of his developing nuclear programme and his increasingly impressive cyber programme may allow the North to effectively get away with smaller provocations without fear of military retaliation.

Mr Kim paid very little price for the cyberattack that took out 70 per cent of Sony Pictures Entertainment's computer systems three years ago. There was no retaliation for its attacks on South Korean banks and media companies; its suspected theft of money from the Bangladesh central bank; or its role in a recent attack that hit Britain's hospitals with ransomware demands. It might try to expand its cyberattacks for profit, or blackmail countries for economic aid.

FOR FUTURE NEGOTIATIONS

Another possibility is that the regime will use its nuclear weapons to gain the upper hand in any future negotiations with the US and its allies.

In the past, negotiators assumed North Korea might be prepared to trade away its nuclear programme in exchange for economic support or a peace treaty with the US, which would mean a final settlement of the seven-decade old conflict on the peninsula.

Under the United Nations armistice that suspended the Korean War in 1953, North Korea is still technically at war with South Korea, and its allies.

But now the hope that sanctions will lead North Korea to give up an arsenal in which it has invested so heavily seems almost a fantasy. Instead, there is talk of whether, as an interim step, Mr Kim might consider a freeze of its programmes at their current level.

If so, the huge buildup of the past few years may have an easy explanation: Before negotiating a freeze, Mr Kim may want a nuclear capability too big to dismantle. In short, he wants to be treated like Pakistan, or India, which have made clear they will never trade away their nuclear arsenals. By and large, the world has stopped demanding that they do so.

ENSURING LOYALTY AT HOME

Domestic politics are also at work. Keeping nuclear weapons is also how the Kim regime can best engender fear and loyalty in the country's populace.

"In order to justify what they've been doing all these years, they need an enemy of the United States to continue to exist," said Ms Suzanne DiMaggio, a director and senior fellow at the New America research group who has been involved in unofficial talks with North Korea. "Once that enemy is gone, then they don't have the rationale any longer to keep this society in complete isolation."

That is not to say that the North Koreans don't have a list of wants if and when they are offered a seat at the negotiating table.

The North has repeatedly called for the suspension of annual war games conducted by the US and South Korea and an eventual withdrawal of US troops from the peninsula. It is likely to want a guarantee that the US will never again station tactical nuclear weapons in South Korea. It will surely want sanctions lifted, and some economic aid, as well as diplomatic recognition.

RECOGNITION AND RESPECT

Critics of past negotiations with North Korea say it will never be satisfied. "It's just this endless slippery slope of demands," said Mr Bruce Klingner, a Korean and Japanese specialist at the Heritage Foundation in Washington.

Some analysts say that what North Korea most wants is respect.

"There is a certain universality of wanting to be recognised and respected," said Mr Cameron Munter, former US ambassador to Pakistan and now president of the EastWest Institute. "And because Americans take this for granted, they don't see just how deeply motivating that search for respect can be."

But granting that wish can be difficult for politicians who do not want to appear to be bowing to a dictator. The farthest Mr Trump went recently was to say at a rally in Phoenix last month that he respected the fact that Mr Kim "is starting to respect us".

If that was ever true, it didn't last long.