(CNN) For years they've been separated by the legacy of war, but on Friday the leaders of South and North Korea staged a rare display of cohesion as they stepped across the line separating the two nations.
At the aptly named Peace House in the demilitarized zone (DMZ) that divides the two countries, North Korean leader Kim Jong Un and South Korean President Moon Jae-in held talks about the future on the Korean Peninsula.
The landmark summit, the first time leaders of the two countries have met since 2007, comes on the back of an unprecedented flurry of international diplomacy that has seen Kim emerge from years of isolation ready to play on a world stage.
All this comes before what's primed to be the most significant diplomatic encounter in a generation when Kim and US President Donald Trump meet in May or early June.
Pyongyang's frantic engagement efforts are a dramatic departure from 2017, when North Korea trumpeted the advances of its nuclear weapons program, threatening the US territory of Guam and claiming its rockets could hit the US mainland.
So what exactly has brought Kim to the table? Is he negotiating from a position of strength or weakness? Here, three experts share their views.
Kim is extremely vulnerable economically, which means he is approaching this negotiation from a position of weakness.
We've seen a collapse in trade with China, with North Korean exports down 95% year on year, at only $9 million in February. Imports were down by about a third to $103 million, including almost nothing of long-term value -- no machinery, cereals, petroleum products, or vehicles.
This is according to official Chinese data -- it may not be completely accurate but it is what Beijing wants everyone to know, which in itself is trouble for Pyongyang. North Korea's overall foreign trade is probably at its weakest since the Korean War, and despite the rhetoric, it is nowhere near self-reliant, especially for food, fuel, and machinery.
At home, the economy faces huge pressures. Unofficially, the dollar, along with China's renminbi, has become more widely circulated, bringing important gains to market activities and private sector productivity, but creating huge problems for the regime, which is concerned the private sector will undermine state control.
This makes it hard to control domestic credit and inflation, since at any time people can decide to cash in their North Korean won for US dollars. This risks a currency collapse which can be orchestrated from outside.
The weak state economy forced Kim to swallow Trump's aggressive posturing, reach out to Seoul and Washington, and take the train to Beijing. We don't know what Xi discussed with Kim, but it could involve some sanctions relief in return for sincere summit talks.
Pyongyang knows that at any time China can cut off delivery of free crude oil, causing inflation to soar. Kim is not stupid enough to risk this, and must come to the table.
This gives the US an opportunity to create major systemic change in North Korea, including ending the hostility brought on by the archaic Stalinist command economy and social system, which prevent normal dealing with the rest of the world.
Bottom line: It's our best chance in at least a generation, since our failure to take advantage of Kim Il Sung's death, the famine, and the collapse of the Soviet Union in the mid-1990s. Kim might not give up his nuclear arsenal, but he may be willing to let it erode or be made unusable. We hold the negotiating advantage. The advantages may thus be ours, but it won't be easy.
William Brown, adjunct professor at Georgetown School of Foreign Service
Kim Jong Un's emergence onto the world stage six years into his leadership is part of a meticulously crafted and methodically executed political strategy.
Content with his nuclear program and his status as a military leader capable of defending his people, he's now turning his attention to international relations -- and is stepping onto the world stage not simply as a young man who inherited leadership of an impoverished country but as a leader backed by a nuclear weapons program that poses a real threat to global security.
He feels confident that his nuclear program will force foreign leaders to treat him as an equal, and get him a seat at the table with the US as a peer, not an underdog.
Simply sitting down for a summit with Moon, and then Trump, leader of the world's most powerful country, will be characterized as a victory back home in North Korea. Neither his father, Kim Jong Il, or his grandfather, Kim Il Sung, held a summit with a sitting US president.
Of course, this position of strength is mainly in terms of propaganda value back home, but Kim's need to settle the question of his authority and leadership within North Korea cannot be discounted. In reality, no matter how Pyongyang spins it, North Korea is a poor country in desperate need of outside help.
Bottom line: Kim is playing a high-stakes game, using nuclear weapons as his trump card, in order to improve his hand in future negations with South Korea and the United States.
Jean H. Lee, director Hyundai Motor-Korea Foundation Center for Korean History and Public Policy
When Kim Jong Un arrives for summits with Moon and Trump, he will have several paths to a win.
Kim will attempt to ease sanctions, harvest legitimacy, and damage the US-South Korea military alliance while offering as few restrictions as possible on his nuclear and missile programs.
The diplomatic overtures are in part a play for time. Pyongyang may have calculated that the risk of war has risen to unacceptable levels and that the best play is to run out the clock on Trump's first term, which has been marked by erratic threats, military displays, and the appointment of hardliners to high positions.
If it ever came to major war, North Korea would inflict massive damage on South Korean, Japanese, and US citizens. But even as it did, the regime would likely sustain enormous losses. Its leaders could lose their grip on power or their lives.
To buy time, North Korea may offer moderate and temporary concessions to limit its nuclear or missile tests programs, offer purely symbolic steps hoping the president will accept them and declare victory for the US, or may try to bog down negotiators in complex technical discussions.
In any case, the idea that diplomatic or military action could immediately and irreversibly dismantle North Korea's nuclear program is a chimera.
Bottom line: If Pyongyang tries to run out the clock, the US must be prepared to use that time to its advantage: demand strict restrictions to limit the threat to US allied territory while we pursue a more restrictive agreements.
As long as North Korea's nuclear and missile programs are not moving forward, time is in everyone's interest. It may be the only plausible outcome that makes the US and its allies more rather than less safe. If Trump succeeded in this, he could fairly call it a win.
Adam Mount, Senior Fellow and Director, Defense Posture Project, Federation of American Scientists