William Tobey, a nuclear non-proliferation expert who has taken part in past Six Party Talks with North Korea, says anyone who claims to perfectly understand the motivations of the North Korean government, and does not live in Pyongyang, is probably blowing smoke.

But Tobey and most experts agree that North Korean leader Kim Jong-un's No. 1 goal is self-preservation. For Kim, the pursuit of nuclear weapons and a missile program is a rational way to stave off attempts by the U.S. to overthrow his regime.

"I think most people ascribe a motivation of regime preservation to their nuclear programs," Tobey said. "So it would be used to deter any attacks that would be aimed at dislodging the government."

Nuclear 'treasure sword'

The North Korean government has said as much in its public statements, Tobey said, and those should be taken "at face value."

A commentary published by North Korea's state KCNA news agency in January last year stated that "history proves that powerful nuclear deterrence serves as the strongest treasure sword for frustrating outsider's aggression."

The piece suggested North Korea fears suffering the same demise as Saddam Hussein's Iraq and Moammar Gadhafi's Libya, that neither could "escape the fate of destruction after being deprived of their foundations of nuclear development and giving up undeclared programs of their own accord."

Philip Yun, a former senior adviser to two U.S. co-ordinators for North Korea at the Department of State, said that he has been in hundreds of hours of negotiations with the North Koreans. "Every single time during that period, they talked about [Slobodan] Milosevic and they talked about Saddam Hussein and subsequently talked about Gadhafi — if they had nuclear weapons they'd still be there."

U.S. President Donald Trump has threatened North Korea with 'fire and fury.' (Pablo Martinez Monsivais/Associated Press)

The latest series of North Korean missile and nuclear weapon tests has sparked a war of words between U.S. President Donald Trump and Pyongyang. Trump has threatened the state with "fire and fury," while North Korea has threatened to strike the U.S. territory of Guam.

Preserving the dynasty

If North Korea truly believes an attack is imminent, it would launch its own strike, believing it has nothing to lose, said Tom Collina, director of policy at Ploughshares Fund, a think-tank dedicated to reducing the dangers of nuclear weapons.

But North Korea would not attack "out of the blue," because it knows that would be suicidal, the end of the regime, he said.

"These people are smart about preserving themselves and their dynasty," Collina said. "They may be willing to starve their people, they may be willing to have everyone in the world be their enemy, but they are survivors."

"The first rule of the Kim dynasty is to preserve the Kim dynasty. And the second rule of the Kim dynasty is to preserve the Kim dynasty."

After the past 60 years, it's unlikely the U.S. could say anything to convince North Korea it has nothing to fear from Washington in terms of regime change, Tobey said.

Part of North Korea's founding narrative is to portray itself as a nation beset by a foreign enemy.

"It's desperately poor, desperately totalitarian. The only thing they've got left is nationalism," Tobey said.

Nuclear pride

The possession of powerful weapons gives North Koreans bragging rights that can engender nationalist pride.

"How many countries have a nuclear device? Not many," said Yun. "How many people can shoot a rocket up into the sky? Not very many. You're part of the nuclear club, and it's better than South Korea, which is not. They don't have these capabilities."

There is also an economic component to the pursuit of weapons, Yun said. Shortly after the death of his father, Kim Jong-un pledged to develop the economy and improve people's livelihoods.

"So he's on the hook for this. He's got to help them. He's at least got to make sure the core elite are with him," Yun said. "The nuclear weapons create a security blanket for him to then concentrate on the economy."

Yun said Trump may be making a significant mistake by sending signals he wants to break the Iran nuclear deal negotiated by former president Barack Obama.

Missile tests by the North and impending military exercises by the South and the U.S. have raised tensions on the Korean Peninsula. (Lee Jin-man/Associated Press)

"[North Korea] will have no incentive to make a deal with us. We're shooting ourselves in the foot with North Korea."

The U.S., he said, must employ a carrot and stick approach, with the first step to get North Korea to freeze its programs.

Tobey said he believes the "no viable options" view is a myth and that the U.S., South Korea and Japan need to step back and take a deep breath. North Korea, he reminded, is a tiny country, with a tiny economy, and it knows the regime would end if it deployed any serious weapons.

"We managed to deter the Soviet Union for decades with basically rough parity in the two military arsenals. There's no comparison with U.S. and North Korea military capabilities. We can deter them."