Before a row of alternating USA and North Korean flags, the leaders shook hands warmly at a Singapore island resort, creating an indelible image of two unorthodox leaders as they opened a conversation that could determine historic peace or raise the specter of a growing nuclear threat.
"President Trump has already started to say that CVID (complete, verifiable and irreversible denuclearization) is unlikely and that this will take some time".
Iran said North Korea should be wary of negotiating with Mr Trump following his withdrawal from the landmark 2015 nuclear agreement. "But we have enough intelligence to know that what they have is very substantial".
Trump sidestepped his public praise for an autocrat whose people have been oppressed for decades.
North Korea tends to keep its official government commentary on the pages of Rodong Sinmun, which routinely threatened nuclear annihilation of the American mainland past year.
The White House said the daylong summit would also include a working lunch and a larger meeting involving aides to both leaders. While it would be "catastrophic" for the United States to forcibly disarm the DPRK, as Defense Secretary James Mattis has acknowledged, no one - not the United States or China or South Korea - thinks North Korea deserves an India deal.
Discussions would focus on "the issue of building a permanent and durable peace-keeping mechanism on the Korean peninsula, the issue of realising the denuclearisation of the Korean peninsula and other issues of mutual concern", KCNA said.
It is an extraordinary turnaround from the rhetoric of previous year, when Trump threatened the North with "fire and fury" and Kim dubbed him a "mentally deranged U.S. dotard".
Trump, Pompeo positive ahead of summit
Past nuclear deals have crumbled over North Korea's reluctance to open its doors to outsiders. Trump advisers cast his actions as a show of strength before the Kim meeting.
As the hours count down to the Tuesday morning meeting, here's a look at what happened in Singapore and the Koreas on Monday.
The formal document signing followed a series of meetings at a luxury Singapore resort. The summit is scheduled to begin with a one-on-one meeting between Kim and Trump, before the pair is joined by officials from their respective administrations.
Members of the North Korean delegation and security leave the St Regis hotel in Singapore, June 11, 2018.
The North Korean leader has previously drawn attention for his extreme security measures. They then resumed their walk. For Kim, one of the chief tasks from the summit - a legitimizing photo-op with a USA president - is now all but guaranteed.
Iranian Foreign Ministry Spokesman Bahram Qassemi said the country welcomes any attempt to restore peace and stability to the Korean Peninsula but at the same time is not optimistic that US President Donald Trump would remain committed to his pledges. Kim has been accused of horrific rights abuses against his people.
Trump, too, has recently sought to minimize expectations, saying additional meetings may be necessary. But he added "our hostages" are back home and testing, research and launches have stopped. He was quoted in a Washington Post article about arrangements for the Singapore summit. Earlier Monday, senior diplomats from the two countries met at a hotel to make final preparations for the summit.
North Korea has said it is willing to deal away its entire nuclear arsenal if the United States provides it with a reliable security assurance and other benefits.
The North has faced crippling diplomatic and economic sanctions as it has advanced development of its nuclear and ballistic missile programs.
The White House said in a statement that discussions between officials from both sides were "ongoing and have moved more quickly than expected" before the 9am meeting on Singapore's Sentosa island.