The historic meeting between Kim Jong-un and Moon Jae-in at the border between their countries was peppered with jokes and at least one apparently unscripted moment.

Mr Kim joked during the summit that he would no longer interrupt his counterpart’s sleep with early morning missile tests as the two leaders held talks on denuclearisation and other issues in Panmunjom, in the demilitarised zone.

The North Korean’s pre-planned crossing into the south was historic – the first by a regime leader in more than half a century – but it was Mr Moon’s unplanned step over the border that took observers by surprise.

As the pair shook hands on the southern side, Mr Moon asked Mr Kim: “You have crossed into the South, but when do I get to go across?”

Footage of the meeting showed his hesitant reaction as the North Korean leader replied: “Why don’t we go across now?”

Hand-in-hand they stepped briefly into North Korea before continuing southward shortly after 9.30am local time.

The border crossings made the summit a “landmark event”, said Colin Alexander, a political communications expert from Nottingham Trent University.

Korea Summit: Kim Jong-un crosses border for historic meeting Show all 25 1 /25 Korea Summit: Kim Jong-un crosses border for historic meeting Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un and South Korean President Moon Jae-in raise their hands after signing on a joint statement Korea Summit Press Pool via AP Korea Summit: Kim Jong-un crosses border for historic meeting Kim Jong-un heads towards Moon Jae-in to shake his hand between the military demarcation line, at the Joint Security Area on the Demilitarized Zone in the border village of Panmunjom in Paju EPA Korea Summit: Kim Jong-un crosses border for historic meeting South Korean President Moon Jae-in and North Korean leader Kim Jong-un hold hands as they cross the military demarcation line EPA Korea Summit: Kim Jong-un crosses border for historic meeting South Koreans react while watching a screen reporting the Inter Korean Summit Getty Korea Summit: Kim Jong-un crosses border for historic meeting South Korean President Moon Jae-in and North Korean leader Kim Jong-un chat as they arrive at the Peace House Reuters Korea Summit: Kim Jong-un crosses border for historic meeting North Korea’s leader Kim Jong-un was escorted by bodyguards from the North to the Military Demarcation Line that divides the two Koreas to meet with his South Korean counterpart at the truce village AFP/Getty Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un crosses the military demarcation line to meet with South Korean President Moon Jae-in AP Korea Summit: Kim Jong-un crosses border for historic meeting Kim Jong-un and Moon Jae-in shake hands Getty Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un and South Korean President Moon Jae-in shake hands after Kim crossing the military demarcation line Getty Korea Summit: Kim Jong-un crosses border for historic meeting South Korean President Moon Jae-in and North Korean leader Kim Jong-un at the Joint Security Area EPA Korea Summit: Kim Jong-un crosses border for historic meeting South Korean President Moon Jae-in and North Korean leader Kim Jong-Un speak with two South Korean children who presented Kim Jong-un with a bouquet of flowers EPA Korea Summit: Kim Jong-un crosses border for historic meeting Moon Jae-in Kim Jong-un pose for photographers at the Joint Security Area (JSA) EPA Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un signs the guest book as South Korean President Moon Jae-in looks on Getty Images Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un’s entry in the guestbook. The writing reads ‘A new history starts now. An age of peace, from the starting point of history’ Korea Summit Press Pool/Pool via Reuters Korea Summit: Kim Jong-un crosses border for historic meeting South Korean President Moon Jae-In and North Korean leader Kim Jong-un talk during their summit meeting at the Peace House EPA Korea Summit: Kim Jong-un crosses border for historic meeting North Korea's leader Kim Jong-un smiles AFP/Getty Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un poses with South Korean President Moon Jae-in for a photo inside the Peace House AP Korea Summit: Kim Jong-un crosses border for historic meeting North Korea’s leader Kim Jong-un talks with South Korea’s President Moon Jae-in AFP/Getty Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un and South Korean President Moon Jae-in prepare to plant a pine tree near the military demarcation line AP Korea Summit: Kim Jong-un crosses border for historic meeting South Korean President Moon Jae-in and North Korean leader Kim Jong-un applaud after planting a tree at the truce village Korea Summit Press Pool/Pool via Reuters Korea Summit: Kim Jong-un crosses border for historic meeting North Korea’s leader Kim Jong-un and South Korea’s President Moon Jae-in take a walk after they planted a tree AFP/Getty Korea Summit: Kim Jong-un crosses border for historic meeting North Korea’s leader Kim Jong-un talks with South Korea’s President Moon Jae-in at a bench on a bridge next to the military demarcation line at the truce village of Panmunjom AFP/Getty Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un and South Korean President Moon Jae-in sign on a joint statement Korea Broadcasting System via AP Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un and South Korean President Moon Jae-in embrace each other after signing on a joint statement Korea Summit Press Pool via AP Korea Summit: Kim Jong-un crosses border for historic meeting North Korean leader Kim Jong-un, left, and South Korean President Moon Jae-in shake hands after their joint announcement AP

He added: “North Korean propaganda claims that the South is a puppet under the control of the US.

“Thus, North Korean military personnel refer to the other side of the border as the ‘American side’. We should not underestimate the significance of a North Korean leader being prepared to step over the line into ‘American’ territory.”

During their private meeting on Friday, Mr Kim told Mr Moon he had come to the summit to end the history of conflict between the countries, a South Korean official said.

He added he would be willing to visit the presidential Blue House in Seoul, invited Mr Moon to Pyongyang, and said he wanted to meet “more often” in future, the official added.

North Korea 'suspends' missile and nuclear tests

But there is widespread scepticism about whether Mr Kim is ready to abandon the nuclear arsenal his country has defended and developed for decades, as what it calls a deterrent against US invasion.

Two previous summits between the leaders of North and South Korea, in Pyongyang in 2000 and 2007, failed to end the North’s weapons programmes or improve relations in a permanent way.

“Today, rather than create results we won’t be able to carry out like in the past, we should make good results by talking frankly about current issues, issues of interest,” Mr Kim said.

On Friday afternoon, the leaders issued a joint declaration to say that North and South Korea would begin talks with a view to signing a peace treaty to formally end the Korean War later this year, 65 years after hostilities ended.

Their encounter came just weeks before Mr Kim is expected to meet with Donald Trump, when the US president plans to make a further push for denuclearisation.

Experts have warned the two sides may have differing ideas about what that means, however.

And Mr Kim’s declaration that he would end nuclear weapons testing was followed by claims the North’s main test site at Punggye-ri under Mount Mantap had collapsed.

Chinese scientists studied a series of earthquakes after Pyongyang’s latest and most powerful experiment, which they believed were caused by collapsing earth.

North Korea: A road trip on the edge of the Chinese border Show all 20 1 /20 North Korea: A road trip on the edge of the Chinese border North Korea: A road trip on the edge of the Chinese border People have their picture taken with North Korea in the background, in Tumen, China. In the Chinese city of Dandong, signs of neighbouring North Korea are pervasive. REUTERS North Korea: A road trip on the edge of the Chinese border A North Korean woman is photographed from the Chinese side of the Yalu River near the town of Changbai, China as she walks between houses in the North Korean town of Hyesan. A week-long road trip along China's side of its border with North Korea revealed stark contrasts between China's bright towns and North Korea's dark villages. REUTERS North Korea: A road trip on the edge of the Chinese border North Korean souvenirs are displayed for sale on the banks of the Yalu River in Dandong in Liaoning province, China. In the Chinese city of Dandong, signs of neighbouring North Korea are pervasive. Reuters North Korea: A road trip on the edge of the Chinese border A large screen, which faces North Korea, broadcasts propaganda videos on an island on the Yalu River between North Korea and China, in the town of Linjiang in Jilin province, China. A week-long road trip along China's side of its border with North Korea revealed stark contrasts between China's bright towns and North Korea's dark villages. REUTERS North Korea: A road trip on the edge of the Chinese border A piece of clothing is used to make a gap in barbed wire near the closed bridge over the Yalu River on the Chinese side of the border with North Korea between towns of Ji'an and Linjiang, China. A week-long road trip along China's side of its border with North Korea showed places where it is porous. 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REUTERS North Korea: A road trip on the edge of the Chinese border Tourists travel on a boat taking them from the Chinese side of the Yalu River for sightseeing close to the shores of North Korea, near Dandong, Liaoning province, China. In the Chinese city of Dandong, signs of neighbouring North Korea are pervasive. REUTERS North Korea: A road trip on the edge of the Chinese border North Koreans are photographed from the Chinese side of the border as they stand next to the freezing Yalu River near the town of Linjiang, China. On a road trip along China's side of its border with North Korea, reporters found a group of North Koreans diving in the Yalu river who the Chinese locals said were searching for gold. REUTERS North Korea: A road trip on the edge of the Chinese border Women walk across a bridge from an island on the Yalu River, dividing North Korea and China, in the town of Linjiang in Jilin province, China. 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REUTERS North Korea: A road trip on the edge of the Chinese border A man looks through binoculars towards North Korea on the Broken Bridge over the Yalu River that connects the North Korean town of Sinuiju and Dandong in Liaoning Province, China. In the Chinese city of Dandong, signs of neighbouring North Korea are pervasive. REUTERS North Korea: A road trip on the edge of the Chinese border North Koreans are photographed from the Chinese side of the border as they stand next to the freezing Yalu River near the town of Linjiang, China. On a road trip along China's side of its border with North Korea, reporters found a group of North Koreans diving in the Yalu river who the Chinese locals said were searching for gold. REUTERS North Korea: A road trip on the edge of the Chinese border North Korean fishermen are seen as a Chinese flag flutters from the Broken Bridge as the sun sets over the Yalu River between the North Korean town of Sinuiju and Dandong in Liaoning Province, China. In the Chinese city of Dandong, signs of neighbouring North Korea are pervasive. REUTERS North Korea: A road trip on the edge of the Chinese border North Koreans are photographed from the Chinese side of the border as they stand in the freezing Yalu River near the town of Linjiang, China. On a road trip along China's side of its border with North Korea, reporters found a group of North Koreans diving in the Yalu river who the Chinese locals said were searching for gold. REUTERS North Korea: A road trip on the edge of the Chinese border Women, photographed from the Chinese side of the border, are seen through binoculars fixed on a building on the Chinese side of the border for sightseers to look across to North Korea, as they cross the bridge from Namyang in North Korea towards the town of Tumen in China, Reuters

The White House said in a statement on Friday it was ”hopeful that talks will achieve progress toward a future of peace and prosperity for the entire Korean peninsula ... [and] looks forward to continuing robust discussions in preparation for the planned meeting between president Donald J Trump and Kim Jong-un in the coming weeks”.

And UK Foreign Secretary Boris Johnson, speaking at Nato headquarters, told reporters he was “very encouraged” by the summit, but added: “I don’t think that anybody looking at the history of North Korea’s plans to develop a nuclear weapon would want to be over-optimistic at this point.

“But it is clearly good news that the two leaders are meeting.”

China, North Korea’s sole major ally, also welcomed the meeting. A foreign ministry spokeswoman said it was a chance to expand into a “new journey of long-term peace and stability on the peninsula”.