Kim Jong Un and Moon Jae-in shake hands as they arrive for the historic inter-Korean summit (Reuters)

Highlights Moon Jae-in said he hoped two Koreas would sign a "a bold agreement"

Last year Pyongyang carried out sixth nuclear blast, by far most powerful

The summit is being viewed as a step forward towards achieving peace

Kim Jong Un became the first North Korean leader to enter the South since the Korean War ended (Reuters)

Kim Jong Un and Moon Jae-in walk across the military demarcation line (Reuters)

Kim Jong Un and Moon Jae-in attend the inter-Korean summit at the truce village of Panmunjom (Reuters)

North Korean leader Kim Jong Un and the South's President Moon Jae-in sat down to a historic summit Friday after shaking hands over the Military Demarcation Line that divides their countries in a gesture laden with symbolism."I am happy to meet you," a smiling Moon told Kim before the visitor stepped over the concrete blocks , making him the first North Korean leader to set foot in the South since the Korean War ended in an armistice 65 years ago.At Kim's invitation the two men briefly crossed hand-in-hand into the North before walking to the Peace House building on the southern side of the truce village of Panmunjom for the summit -- only the third of its kind since hostilities ceased in 1953."I came here determined to send a starting signal at the threshold of a new history," Kim told Moon as the meeting began, promising a "frank, serious and honest mindset".With the North's atomic arsenal high on the agenda, Moon responded that he hoped they would reach " a bold agreement so that we may give a big gift to the whole Korean people and the people who want peace".Kim was flanked by his sister and close adviser Kim Yo Jong and the North's head of inter-Korean relations, while Moon was accompanied by his spy chief and chief of staff.The two men briefly stepped back over the line into the North before walking to the Peace House building on the southern side of the truce village of Panmunjom for the summit -- only the third of its kind since hostilities ceased in 1953.It is the highest-level encounter yet in a whirlwind of nuclear diplomacy, and intended to pave the way for a much-anticipated encounter between Kim and US President Donald Trump.The North's official KCNA news agency said that Kim will "open-heartedly discuss... all the issues arising in improving inter-Korean relations and achieving peace, prosperity and reunification of the Korean peninsula".It did not mention denuclearisation.Last year Pyongyang carried out its sixth nuclear blast, by far its most powerful to date, and launched missiles capable of reaching the US mainland.Its actions sent tensions soaring as Kim and Trump traded personal insults and threats of war.Moon seized on the South's Winter Olympics as an opportunity to broker dialogue between them, and has said his meeting with Kim will serve to set up the summit between Pyongyang and Washington.The White House said in a statement it hoped the summit would it would "achieve progress toward a future of peace and prosperity for the entire Korean Peninsula".Trump has demanded the North give up its weapons , and Washington is pressing for it to do so in a complete, verifiable and irreversible way.But Seoul played down expectations Thursday, saying the North's technological advances with its nuclear and missile programmes meant any deal would be "fundamentally different in nature from denuclearisation agreements in 1990s and early 2000s"."That's what makes this summit all the more difficult," the chief of the South's presidential secretariat Im Jong-seok told reporters.Pyongyang is demanding as yet unspecified security guarantees to discuss its arsenal.When Kim visited the North's key backer Beijing last month in only his first foreign trip as leader, China's official Xinhua news agency cited him saying that the issue could be resolved, as long as Seoul and Washington take "progressive and synchronous measures for the realisation of peace ".In the past, North Korean support for denuclearisation of the "Korean peninsula" has been code for the removal of US troops from the South and the end of its nuclear umbrella over its security ally -- prospects unthinkable in Washington."The big issues we know are peace and denuclearisation," Yonsei University professor John Delury told AFP.The two Koreas "can do a lot more on peace than on denuclearisation", he said, but the post-summit statement will give "a lot of chance to analyse every word, reading between the lines, look for things that are there and not there".Pyongyang announced last week a moratorium on nuclear tests and intercontinental ballistic missiles , adding it would dismantle its Punggye-ri nuclear test site But it also said it had completed the development of its weapons and had no need for further tests.Seoul has also promoted the idea of opening talks towards a peace treaty to formally end the 1950-53 Korean War, when hostilities stopped with a ceasefire, leaving the neighbours technically in a state of conflict.Reunions of families left divided by the war could also be discussed at the summit, and Moon has told Japanese Prime Minister Shinzo Abe he will raise the emotive subject of Japanese citizens kidnapped by the North.The North Koreans were expected to cross back to their side for lunch, and before the afternoon session, Moon and Kim were to engage in a symbolic tree planting ceremony on the demarcation line.The soil will come from Mount Paektu, on the North's border with China, and Mount Halla, on the South's southern island of Jeju.After they sign an agreement a joint statement will be issued, with a banquet and farewell ceremony to follow in the evening before Kim returns to the North.