On Friday, Kim Jong-un stepped over the border into South Korea.

It was a huge moment — the first time since 1953 that a North Korean ruler had entered its southern neighbour with whom it's officially still at war.

The countries agreed to work towards the denuclearisation of the Korean Peninsula and the establishment of peace.

But for many observers, the imagery of the one-day summit was as significant. Here's how it all happened.

Mr Kim stepped across the border on Friday morning

It was the moment that had looked so unlikely until so recently. This video captured it:

Sorry, this video has expired Kim Jong-un arrives in South Korea ahead of summit

It's the most heavily armed border in the world, and the first time it's been crossed by a ruler from the Kim dynasty since the signing of the Korean War armistice in 1953.

But also significant was Mr Kim going off script, taking the hand of South Korean President Moon Jae-in and stepping across with him into the northern side.

In the words our China correspondent Bill Birtles, "A young leader long ridiculed abroad as a caricature showed his sophistication".

Kim Jong-un and Moon Jae-in walk together at the border village of Panmunjom. ( AP: Korea Summit Press Pool )

It was a carefully stage-managed event. The two leaders were then handed flowers by a South Korean boy and girl from the border-truce village of Panmunjom, where the summit was held.

Walking on a red carpet rolled out for the two heads of state, the pair were met by a South Korean honour guard in historical costumes and playing traditional music.

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Mr Kim signed a guestbook as he arrived for the summit

This is what he wrote:

"New history starts from now, at the historic starting point of an era of peace."

Later, Kim joked that he hoped Mr Moon would enjoy North Korea's famous cold noodles at the banquet after the summit, saying it was difficult to bring them from the capital Pyongyang.

He then turned to his sister sitting to his left and said "maybe I shouldn't have said [Pyongyang] was far".

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Mr Kim's sister was given a place at the negotiating table

Kim Yo-jong was at the negotiating table alongside her brother. ( AP: Korea Summit Press Pool )

Kim Yo-jong has become the most visible member of the North Korean regime after her brother — she travelled to the South in early February for the Olympics.

She was in the delegation as Mr Kim walked across the line that divides the two Koreas, and took a seat beside him as he started his first round of talks at the summit.

The only other North Korean official present was former intelligence chief Kim Yong Chol, the top official in charge of relations with the South.

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Mr Kim and Mr Moon planted a tree as a symbol of peace

They planted the pine tree during a break in the summit, unveiling a stone plaque next to it which was engraved with a message saying "Peace and Prosperity Are Planted".

The pine tree dates to 1953, the year the fighting stopped. The soil and water were brought from the Koreas' mountains and rivers.

Sorry, this video has expired South and North Korean leaders plant tree in symbolic act

Mr Moon said he'd like to visit Mount Paektu

Mr Kim responded that the trip to the mountain near North Korea's border with China would be uncomfortable given current transport conditions, but the North would improve its networks should Mr Moon decide to visit.

He also said that the North Korean delegation had come back from the Winter Olympics impressed by the South's bullet train services.

Mr Moon said the people of both Koreas would be able to enjoy high-speed train services if relations improve and the countries connect their rail networks.

According to a senior South Korean presidential official, Mr Kim joked to Mr Moon during a conversation that he was sorry for waking him up with his early morning missile tests.

At the end of the talks, the two countries announced they had agreed to rid their peninsula of nuclear weapons

However, a joint statement issued after the meeting failed to provide any new specific measures on how to achieve the goal of "a nuclear-free Korean Peninsula through complete denuclearisation".

North Korea has previously used the term "denuclearisation" to say it can disarm only when the United States withdraws its 28,500 troops in South Korea.

The two countries also said they would jointly push for talks with the United States and also potentially China to officially end the 1950-53 Korean War. (Technically, it didn't end. The fighting stopped when North Korea, China and the US reached an armistice.)

They said they hoped to declare an official end to the war by year's end.

North Korean leader Kim Jong Un applauds alongside his wife Ri Sol Ju. ( Reuters: Korea Summit Press Pool )

Other announcements made included:

Starting May 1, both countries will suspend all loudspeaker propaganda broadcasts across the border and dismantle broadcasting equipment

Starting May 1, both countries will suspend all loudspeaker propaganda broadcasts across the border and dismantle broadcasting equipment They will stop dropping propaganda leaflets across the border

They will stop dropping propaganda leaflets across the border They will guarantee the safe operations of fishermen from both the North and South

They will guarantee the safe operations of fishermen from both the North and South They have agreed for Mr Moon to visit Pyongyang later this year

They have agreed for Mr Moon to visit Pyongyang later this year Mr Moon and Mr Kim will meet on a regular basis and exchange calls via a recently established hotline

Mr Moon and Mr Kim will meet on a regular basis and exchange calls via a recently established hotline The Koreas will seek to expand civilian exchanges and pursue joint sports and cultural events

The Koreas will seek to expand civilian exchanges and pursue joint sports and cultural events Family reunions will take place for people separated by the war

The leaders attended a farewell banquet

Invited to the dinner were famous cultural figures from both countries, including the North's Hyon Song Wol, the leader of Kim's hand-picked Moranbong girl band, and South Korean pop star Cho Yong-pil.

As pop music blared, Mr Kim and Mr Moon firmly grasped each other's hands as photos of their summit were projected onto a massive screen installed in front of the building where they met.

Mr Kim then got inside a black Mercedes Benz limousine that drove him back to the North.

Kim Jong-un waves as he leaves the farewell ceremony. ( Reuters: Korea Summit Press Pool )

ABC/wires