With the highly symbolic gesture, Trump became the first sitting US president to set foot on North Korean soil.

What originally was intended to be an impromptu exchange of pleasantries turned into a 50-minute meeting, another historic first in the yearlong rapprochement between the two nations, which are still technically at war with each other.

Trump announced afterward that the two nations had agreed to resume discussions in the coming weeks.

Significant doubts remain, though, about the future of the negotiations and the North’s willingness to give up its stockpile of nuclear weapons.

“Stepping across that line was a great honour,” Trump said at a joint news conference with Kim. “It’s a great day for the world,” he added.

“I want to thank Chairman Kim for something else; when I put out the social media notification, if he didn’t show up the press was going to make me look very bad so you made us both look good and I appreciate it,” Trump added.

“We’ve developed a great relationship, I think if you go back two and a half years and you look at what was going on prior to me becoming president, it was a very, very bad situation a very dangerous situation for South Korea, North Korea, for the world,” the US president said.

“I think the relationship that we have developed has meant so much to so many people, and it’s just an honour to be with you and it was an honour that you asked me to step over that line and I was proud to step over the line,” he added.

‘First US president to visit’

Standing next to Trump after the US president crossed the border, Kim noted the historic value of the meeting.

“President Trump has just walked across the demarcation line, making him the first US president to visit our country…

“This meeting is a symbol of separation between South and the North and a reminder of the unfortunate past… Meeting in such place shows that we are willing to put an end to the unfortunate past and also open a new future,” Kim said.

Trump arrived in Seoul late on Saturday for talks with South Korea‘s President Moon Jae-in after attending a G20 summit in Osaka, Japan, during which he made a surprise, spur-of-the-moment offer to meet Kim.

“We’re going to the DMZ border and I’ll be meeting with Chairman Kim,” Trump said earlier.

“I look forward to it very much. We’ve developed a very good relationship,” Trump said, hailing a “certain chemistry” between the two leaders.

Trump and Kim attended a short news conference after meeting at the DMZ [Reuters]

But he was “in no rush” when it came to tensions on the Korean Peninsula, Trump said, and stressed the meeting would be short.

“Just shake hands quickly and say hello because we haven’t seen each other since Vietnam,” he said, referring to a summit that collapsed without an agreement in February.

“It’s just a step and probably a step in the right direction,” said Trump.

Moon said that while he would also go to the DMZ, the “focus” would be on the Trump-Kim encounter, with a possibility of a more formal sit-down at a later date.

“I think when the third US-North summit will be held depends on what change today’s meeting and dialogue could generate,” said Moon.

Moon said that “peace takes more courage compared to tensions”.

“Continued dialogue is very practical and the only method to bring about peace on the Korean Peninsula,” added the South Korean president.

Trump and Kim each stepped over the border into North and South Korea [Reuters]

Al Jazeera’s diplomatic editor James Bays, reporting from Paju, South Korea near the DMZ, said the meeting was “historic”.

“Yes, it’s only a step, but it is the first step by a sitting US president on North Korean soil since the Korean War, in fact, since the division of Korea, the creation of North Korea almost 75 years ago.”

Moon, who is heavily invested in the peace process, has tied his political future to it, Bays said.

“Everything for him politically is in on this peace initiative. He is saying already that President Trump is going to go down in history as the president who brought peace to North Korea,” he added.

Vietnam breakdown

Trump and Kim last met in Hanoi, Vietnam, in February but the talks ended abruptly and a joint signing ceremony was cancelled.

North Korea said it had asked for partial sanctions relief in return for closing its main nuclear site at Yongbyon, an important nuclear-fuel production facility but not the only place North Korea is believed to make bomb fuel.

The US has been spinning the summit breakdown, with senior officials saying that North Korea wanted billions of dollars in sanctions relief in return for only partial dismantlement of Yongbyon, and demanded North Korea scrap more of its nuclear programme for such a high level of concessions.

North Korean officials denied they demanded sanctions be removed entirely.

The North Korean leader also warned that the situation “may return to its original state as the US took a unilateral attitude in bad faith at the recent second DPRK-US summit talks”.

“Peace and security on the Korean Peninsula will entirely depend on the US future attitude, and the DPRK will gird itself for every possible situation,” KCNA quoted Kim as saying in April.

The Marine One helicopter carrying Trump to the DMZ takes off from Seoul [Jacquelyn Martin/Reuters]