Donald Trump returning to the White House would be “a once-in-a-thousand-year opportunity” for North Korea, according to a man in a unique position to know.

Ri Il Kyu is the highest-ranking defector to escape North Korea since 2016 and has been face to face with Kim Jong Un on seven separate occasions.

The former diplomat, who was working in Cuba when he fled with his family to South Korea last November, admits to "shivering with nerves" the first time he met Kim Jong Un.

But during each meeting, he found the leader to be “smiling and in a good mood”.

“He praised people often and laughed. He seems like an ordinary person,” Mr Ri tells the BBC. But he is in no doubt Mr Kim would do anything to guarantee his survival, even if it meant killing all 25 million of his people: “He could have been a wonderful person and father, but turning him into a god has made him a monstrous being.”

In his first interview with an international broadcaster, Mr Ri provides a rare understanding of what one of the world’s most secretive and repressive states is hoping to achieve.

He says that North Korea still views Mr Trump as someone it can negotiate with over its nuclear weapons programme, despite talks between him and Kim Jong Un breaking down in 2019.

Mr Trump has previously hailed the relationship with Kim as a key achievement of his presidency. He famously said the two “fell in love” exchanging letters. Just last month, he told a rally Mr Kim would like to see him back in office: “I think he misses me, if you want to know the truth.”

North Korea is hoping it can use this close personal relationship to its advantage, says Mr Ri, contradicting an official statement from Pyongyang last month that it “did not care” who became president.

The nuclear state will never get rid of its weapons, Mr Ri says, and would probably seek a deal to freeze its nuclear programme in return for the US lifting sanctions.

But he says Pyongyang would not negotiate in good faith. Agreeing to freeze its nuclear programme “would be a ploy, 100% deception”, he says, adding that this was therefore a “dangerous approach” which would “only lead to the strengthening of North Korea”.

Eight months after his defection, Ri Il Kyu is living with his family in South Korea. Accompanied by a police bodyguard and two intelligence agents, he explains his decision to abandon his government.

After years of being ground down by the corruption, bribery and lack of freedom he faced, Mr Ri says he was finally tipped over the edge when his request to travel to Mexico to get an operation on a slipped disc in his neck was denied. “I lived the life of the top 1% in North Korea, but that is still worse than a middle-class family in the South."

As a diplomat in Cuba, Mr Ri made just $500 (£294) a month and so would sell Cuban cigars illegally in China to make enough to support his family.

When he first told his wife about his desire to defect, she was so disturbed she ended up in hospital with heart problems. After that, he kept his plans secret, only sharing them with her and his child six hours before their plane was due to depart.

He describes it as a “life-or-death gamble”. Regular North Koreans who are caught defecting would typically be tortured for a few months, then released, he says. “But for elites like us, there are only two outcomes - life in a political prison camp or being executed by a firing squad."

“The fear and terror were overwhelming. I could accept my own death, but I could not bear the thought of my family being dragged to a gulag,” he says. Although Mr Ri had never believed in God, as he waited nervously at the airport gate in the middle of the night, he began to pray.

The last known high-profile defection to the South was that of Tae Yong-ho in 2016. A former deputy ambassador to the UK, he was recently named the new leader of South Korea's presidential advisory council on unification.

Turning to North Korea’s recent closer ties with Russia, Mr Ri says the Ukraine war had been a stroke of luck for Pyongyang. The US and South Korea estimate the North has sold Moscow millions of rounds of ammunition to support its invasion, in return for food, fuel and possibly even military technology.

Mr Ri says the main benefit of this deal for Pyongyang was the ability to continue developing its nuclear weapons.

With the deal, Russia created a "loophole" in the stringent international sanctions on North Korea, he says, which has allowed it “to freely develop its nuclear weapons and missiles and strengthen its defence, while bypassing the need to appeal to the US for sanctions relief”.

But Mr Ri says Kim Jong Un understands this relationship is temporary and that after the war, Russia is likely to sever relations. For this reason, Mr Kim has not given up on the US, Mr Ri says.

“North Korea understands that the only path to its survival, the only way to eliminate the threat of invasion and develop its economy, is to normalise relations with the United States."

While Russia might have given North Korea a temporary respite from its economic pain, Mr Ri says the complete closure of North Korea’s borders during the pandemic “severely devastated the country’s economy and people’s lives”.

When the borders reopened in 2023 and diplomats were preparing to return, Mr Ri says families back home had asked them to “bring anything and everything you have, even your used toothbrushes, because there is nothing left in North Korea”.

The North Korean leader demands total loyalty from his citizens and the mere whiff of dissent can result in imprisonment. But Mr Ri says years of hardship had eroded people’s loyalty, as no-one now expected to receive anything from their “Supreme Leader” Kim Jong Un.

“There is no genuine loyalty to the regime or to Kim Jong Un anymore, it is a forced loyalty, where one must be loyal or face death,” he says.

Recent change has largely been driven by an influx of South Korean films, dramas and music, which have been smuggled into the North and are illegal to watch and listen to.

“People don’t watch South Korean content because they have capitalist beliefs, they are simply trying to pass the time in their monotonous and bleak lives,” Mr Ri says, but then they begin to ask, “Why do those in the South live the life of a first-world country while we are impoverished?"

But Mr Ri says that although South Korean content was changing North Korea, it would not bring about its collapse, because of the systems of control in place. “Kim Jong Un is very aware that loyalty is waning, that people are evolving, and that’s why he is intensifying his reign of terror,” he says.

The government has introduced laws to harshly punish those who consume and distribute South Korean content. The BBC spoke to one defector last year who said he had witnessed someone be executed after sharing South Korean music and TV shows.

North Korea’s decision, at the end of last year, to abandon a decades-old policy of eventually reunifying with the South, was a further attempt to isolate people from the South, Mr Ri says.

He describes this as Kim Jong Un’s “most evil act”, because all North Koreans dream of reunification. He says that while North Korea’s past leaders had “stolen people’s freedom, money and human rights, Kim Jong Un has robbed what was left of them: hope”.

Outside North Korea, much attention is paid to Kim Jong Un’s health, with some believing that his premature death could trigger the collapse of the regime. Earlier this week, South Korea’s intelligence agency estimated that Mr Kim weighed 140kg, putting him at risk of cardiovascular disease.

But Mr Ri believes the system of surveillance and control is now too well established for Kim’s death to threaten the dictatorship. “Another evil leader will merely take his place,” he says.

It has been widely speculated that Mr Kim is grooming his young daughter, thought to be called Ju Ae, to be his successor, but Mr Ri dismisses the notion.

Ju Ae, he says, lacks the legitimacy and popularity to become the leader of North Korea, especially as the sacred Paektu bloodline, which the Kims use to justify their rule, is believed to run only through the men of the family.

At first, people were fascinated by Ju Ae, Mr Ri says, but not any more. They question why she was attending missile tests rather than going to school, and wearing luxury, designer clothes instead of her school uniform, like other children.

Rather than waiting for Mr Kim to become ill or die, Mr Ri says the international community has to come together, including North Korea’s allies China and Russia, to “persistently persuade it to change”.

“This is the only thing that will bring about the end of the North Korean dictatorship," he adds.

Mr Ri is hoping that his defection inspires his peers, not to defect themselves, but to push for small changes from the inside. He does not have lofty ambitions, that North Koreans will be able to vote or travel, merely that they can choose what jobs to work, have enough food to eat and be able to share their opinions freely among friends.

For now, though, his priority is helping his family settle into their new life in South Korea and for his child to assimilate into society.

At the end of our interview, he poses a scenario. “Imagine I offer you a venture and tell you, if we succeed we win big, but if we fail it means death.

“You wouldn’t agree, would you? Well that is the choice I forced upon my family, and they silently agreed and followed me,” he says.

“This is now a debt I must repay for the rest of my life.”

Additional reporting by Jake Kwon and Hosu Lee