On March 26, a crew from Japan’s Nippon TV filmed an old-fashioned, dark green train’s arrival in Beijing. The footage prompted much speculation about the identity of the passengers onboard, as the train was coming from North Korea and its arrival caused Chinese authorities to tighten security around the train station and the Chinese capital. Two days later, on March 28, China’s official news agency Xinhua finally announced that the green train had been carrying North Korean leader Kim Jong-un and his wife Ri Sol-ju on their first foreign trip since Kim came to power in 2011.

The news caused an international media frenzy and launched numerous think pieces about North Korea and China’s intentions in the run-up to the two highly publicised summits: one between Kim and South Korean President Moon Jae-in in April, and the other between Kim and US President Donald Trump in May.

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In South Korea, however, the news about Kim’s visit was received with nothing more than a shrug. The close ties between Beijing and Pyongyang were already known, so it was not a shock for South Koreans to learn that Kim wanted to have a face-to-face meeting with China’s President Xi Jinping at this critical juncture.

More than anything, the visit confirmed what many observers here have believed all along: North Korea is serious about dialogue and wants to shed its long-standing image as a pariah state. It is ready to join the international community once again.

It may seem incredible how quickly things have turned around on the Korean Peninsula since the peak of tensions last year. Pyongyang was trading verbal tirades with Washington and conducting weapons tests as late as November. The Trump administration was hardly blameless, ratcheting up its rhetoric and giving rise to concerns that war was imminent.

The hostility seemed to have dissipated overnight, when Kim floated in his new year’s address the idea of sending a delegation to the South for the Pyeongchang Olympics in February. Kim indeed sent his sister and top diplomat to attend the opening ceremony. South Korea reciprocated by dispatching a delegation of its own in early March. The result was an announcement that caught many off-guard: Kim was willing to commit to denuclearisation and was going to attend the third-ever inter-Korean summit in history. He also invited Trump to a meeting, which the US president quickly accepted.

Surprising as that development might have been, North Korea’s 180-degree turn was in every way in keeping with the country’s past behaviour: alternating between confrontation and conciliation. Before starting any negotiation, Pyongyang is always eager to strengthen its bargaining position, which it did in this case by testing what is widely believed to be an intercontinental ballistic missile and declaring itself a nuclear state in November. Its belligerence was in itself a sign that a change in the regime’s tone was due.

And South Korea had kept open the possibility of dialogue so that North Korea could reach out without losing face: Since taking office last May, South Korean President Moon Jae-in invited North Korea to the Olympics multiple times and stressed the importance of dialogue even as he joined the US in supporting more sanctions. That open-arms policy meant Pyongyang could initiate dialogue at any time once it chose to do so.

Improving inter-Korean relations has been a big concern for the Moon administration from the very beginning. For the important post of heading the National Intelligence Service (NIS) – the country’s main spy agency – the government appointed Suh Hoon, who was involved in arranging the two previous summits with North Korea in the 2000s. Suh also lived in Pyongyang for two years in the 1990s while the international community tried to build light-water reactors for North Korea in exchange for shutting down the weapons programme.

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The NIS’s duties include handling the delicate task of communicating with North Korea, at least unofficially. Suh was among the South Korean delegates who visited Pyongyang on March 5 and secured a pledge from North Korea to seriously consider giving up its nuclear programme.

Kim Jong-un’s Beijing visit comes at a time hardliners in both Washington and Seoul are spreading scepticism about North Korea’s commitment to denuclearisation. Can Pyongyang really be trusted after all these years? But such a question betrays foolishness on the part of those who ask it in the first place. It assumes continuity in the regime’s thinking regardless of who is in charge. One would not try to guess Trump’s behaviour based on Barack Obama‘s track record since they are obviously two very different leaders. Yet, when it comes to North Korea, the tendency in the English-speaking pundit circle is to lump its three successive leaders together as though they think as one, and to presuppose that North Korea is fundamentally incapable of change.

Lee Jong-seok, South Korea’s former unification minister and Deputy Secretary-General of the National Security Council, says Kim Jong-un could not be more different from his father and North Korea’s previous leader Kim Jong-il, who was mainly interested in “exaggerated slogans and self-aggrandising”. “Kim Jong-un is a cold pragmatist”, Lee said at a forum I organised on Thursday. Even though improving the national economy is one of Pyongyang’s top priorities, Kim Jong-un excluded economic officials from his Beijing entourage “to show that denuclearisation comes first” and “to avoid misunderstanding” that he was courting China simply to ease the current sanctions, Lee added.

To show seriousness, Kim even made the point of being quoted by Xinhua as saying, “It is our consistent stand to be committed to denuclearisation on the peninsula,” and somewhat implausibly justifying this change in position as “the will” of his late father and grandfather, in order to create a domestic rationale.

With North Korea obviously committed to a different approach, the high-level talks between the two Koreas on Thursday to prepare for the upcoming summit went off without a hitch. The two sessions lasted less than one hour and 30 minutes respectively, and a joint statement confirming the summit date as April 27 emerged by early afternoon.

A headache for South Korea now is not Pyongyang or Beijing, but the Trump administration, which has been quick to take credit for the current rapprochement but never hesitated to question North Korea’s motives throughout. Sounding every bit the self-serving businessman he is known to be, Trump said on Thursday that he might even use the renegotiation of his country’s free trade agreement with South Korea – currently ongoing – to force Seoul to change its North Korea policy. Trump’s appointment of known hardliner John Bolton as his new national security adviser is another source of worry.

About one month is left before the inter-Korean summit in late April, and that is hopefully enough time to make the US see reason. If North Korea can change, why not the US? But Washington has never been so volatile, and the fear is that it will torpedo the fragile path towards peace.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.