SEOUL (CNN) - In a matter of months, North Korea's Kim Jong Un has emerged from years of isolation ready to play on the world stage -- a rapid transformation that has taken many by surprise.
At the end of 2017, the international community implemented its toughest ever sanctions on Pyongyang, as the country conducted more missile and nuclear tests than at any other time in its history.
Now, US President Donald Trump and South Korea's Moon Jae-in are set to meet with Kim. The young North Korean ruler has made his first foreign trip to meet President Xi Jinping in Beijing, and there are also murmurs that Japanese and Russian leaders want an audience.
But past rounds of international negotiations over North Korea's nuclear weapons program ended in failure, and observers warn that the regime has a track record of extracting concessions without giving much in return, in order to ensure the survival of the Kim family dynasty.
"The whole world has underestimated Kim Jong Un and North Korea," says a former North Korean professor who still has family in the country and wanted to remain unidentified. He defected in 2014 and now lives in Seoul.
"Looking back, we know how many people predicted North Korea's imminent collapse when Kim Jong Il died, but the Kim regime is still there and going strong."
Professor Andrei Lankov, a North Korean expert from Kookmin University in Seoul, says Kim Jong Un's behavior reflects what North Korea has always done when they want to squeeze concessions from the other side.
"They begin to behave in a highly risky and irrational way, creating an acute sense of crisis," he says.
"When almost everybody is beginning to wonder whether North Koreans are really going to strike, or start a war, or do something, North Korea suddenly suggests negotiations, and then extracts concessions for their willingness to go back to the status quo."
Despite this assessment, Lankov admits to being "mildly optimistic" about recent events, adding an imperfect deal is better than no deal at all.
Global leaders underestimate North Korea at their peril, if recent history is any guide.
Kim Il Sung, the founder of North Korea and grandfather of the current leader, managed to exploit a breakdown of relations between China and the Soviet Union in the late 1950s and 1960s to his advantage.
Kim Il Sung signed treaties with both, without the other knowing, in the process extracting political and economic gains from both.
"North Korea shares a border with both [China and the then Soviet Union] ... those are two key patrons, allies, trading partners ... [signing treaties with both] took an extraordinary sophistication on Kim Il Sung's part," says John Delury, a professor at Seoul's Yonsei University.
His son Kim Jong Il took power in 1994 when the economy was in a tailspin after the Soviet Union, one of its main benefactors, collapsed, and relations with the United States were at a low.
A deadly famine gripped the country killing up to 2 million people.
Yet just six years later, Kim Jong Il welcomed the South Korean President Kim Dae-jung to Pyongyang for their first-ever summit, followed by the US Secretary of State Madeleine Albright, massive propaganda coups for the leader of a country many assumed would collapse after the hereditary succession.
"Essentially bargaining from a position of such weakness I'd say in the '90s that's pretty remarkable," says Delury. "So, it's in the genes, you shouldn't underestimate North Korea in its sophistication."
Kang Myung-do, who defected in 1994, knows how the Kim family regime works. He was once part of the North Korean elite, the son-in-law of a former Prime Minister.
"All the elites, everyone around Kim Jong Un, are master manipulators and experts," says Kang, who's now a professor of North Korea studies at Kyonggi University.
"Even though their ICBM [intercontinental ballistic missile] technology is not complete, they announced to the world that they are able to reach the US, New York, Washington etc ... Now the US has to see it as their problem. North Korea pulled them into it, so they are in the game now."
Kang believes once Kim Jong Un felt he had enough to bargain with, he used the Pyeongchang Winter Olympics in South Korea to start playing the diplomacy card. "It worked well, Kim Jong Un is smart."
North Korea accepted President Moon's long-standing invitation to attend the Games held in February, sending Kim Yo Jong, Kim Jong Un's sister, among the high-level delegations.
She was the first member of the Kim family to visit South Korea.
As for the summit between Trump and Kim, which is expected to take place in May or early June, Lankov says the US President will be seeing a true negotiator at work.
"The North Korean elite is fighting for their survival," he says. "Regime collapse is likely to mean death for them, a war is likely to mean death -- the Americans are under much less pressure."
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