Seventy-two hours was all it took to rip up the rule book for international relations – or at least the chapter on Northeast Asia.

In the space of just three days, a once unthinkable scenario unfolded as North Korea accepted an invitation from the South for a summit and extended its own invite to the United States.

Even if nothing further happens, this alone is a game changer. That these three leaders – America’s Donald Trump, the North’s Kim Jong-un and the South’s Moon Jae-in – have cleared the way to meet each other raises hopes for a peaceful solution to the North Korea nuclear crisis.

And if the summits do take place as planned, the whole theatre of regional affairs could be transformed with new lead actors and supporting casts.

For South Korea, there is much to win, but it will not be easy. As the Trump-Kim summit follows the inter-Korean summit, Seoul must tread carefully. Should its conduct in the first set of talks upset the North, it risks scuppering the subsequent summit – something that would leave it isolated and attract distrust from neighbouring states.

Why the Trump-Kim meeting hinges on China

Another obstacle for Seoul is that its stance on Pyongyang’s nuclear programme contradicts that of the US. The South will be satisfied with a freeze on the programme, whereas the US wants complete, verifiable and irreversible dismantlement of Kim’s nuclear weapons.

Meanwhile, President Moon Jae-in has his own reasons for wanting the summits and these are to do with his personal aspirations.

Moon wants to resuscitate the inter-Korean summit that has been shelved for the past 10 years under the conservative former leaders Park Geun-hye and Lee Myong-back. As soon as the Pyeongchang Winter Olympic Games had ended, Moon was fast-tracking the inter-Korean summit as the ultimate goal of his tenure. He told the world of his hopes for the summit during his presidential campaign and has followed up his promise since. On March 7, just 10 days after the Games finished, his special envoy to Pyongyang succeeded in securing his prize.

Moon’s obsession with the summit can be attributed to two factors. One factor is his family ties to North Korea. As a descendant of a family that fled the North during the Korean war, Moon cannot help be sympathetic towards, and nostalgic for, the North. The second factor is his personal political beliefs. He is a firm believer in the “sunshine policy” towards Pyongyang, the gist of which is that by helping the North to build its economy the South can make peace on the peninsula possible.

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As far as his political beliefs go, Moon has claimed to be in the “driver’s seat” regarding the whole denuclearisation process – and so far his efforts appear to be bearing fruit. If the two summits are held successfully, Moon will get much credit.

Trump and Kim, too, stand to gain credit. It is not unthinkable that they could revive headlines like those that greeted former US president Richard Nixon’s visit to Beijing in 1972, dubbed “The week that changed the world.”

Trump in particular stands to gain, which is presumably why he accepted Kim’s invitation without hesitation. His hope will be that Washington can undercut its dependence on Beijing in its dealings with Pyongyang.

And for Kim, directly engaging with Washington facilitates Pyongyang’s long-held goal of becoming diplomatically self-reliant.

What key players want from Trump-Kim talks (and what they’ll get)

That leaves Beijing as something of a loser, as the talks signify the undermining of China’s position and influence in regards to North Korean affairs. This could happen in one of three ways. One is Pyongyang jettisons Beijing completely. Another is the two drift apart due to the wave of changes in North Korea’s internal and external circumstances. A third is that Beijing may inadvertently lose its grip on Pyongyang due to its lack of support (and a degrading of trust).

Both summits are high risk, high return. Trump will be the biggest winner, as his “America First” policy will be vindicated in its promise not to repeat past mistakes and to seize the initiative in dealing with China. Kim will be next up as his regime will have gained a sense of security. But Moon may find he is a winner and a loser. If the summits are successful, he may lose the limelight, even as he gains his prize.

Jaewoo Choo is a professor of Chinese foreign policy at Kyung Hee University