During his stroll, crowds yelled out Kim's name and jostled to take pictures, and the North Korean leader posed for a selfie with Singapore officials.
USA and North Korean officials held marathon talks on Monday to finalize details of a nuclear agreement ahead of their leaders' summit the following day.
Despite the White House releasing on 24 May a letter from US President Donald Trump to North Korean Supreme Leader Kim Jong-un stating that Trump was withdrawing from the summit, preparatory talks resumed and Trump and Kim arrived in Singapore on 10 June.
The summit has raised hopes of progress towards a peace treaty to formally end the Korean War, the last festering legacy of the Cold War, after hostilities only stopped with an armistice.
Sanctions on North Korea would remain in place until that happened, Pompeo said on Monday. Trump and Kim Jong Un signed a "comprehensive" and "historic" document after their summit, but the details of that document have not yet been specified. For Kim, one of the chief tasks from the summit - a legitimizing photo-op with a US president - is now all but guaranteed.
In his conference speech, he said North Korean leaders were driven by their desire to stay in power.More news: Bitcoin crash accelerates as Tether fingered
"I feel that Kim Jong-un wants to do something great for his people", he said.
Even so, the summit continues to be a sensitive topic in North Korea and it is hard - even more so than usual - to get people to express opinions about it.
Up early in Singapore, Trump tweeted with cautious optimism: "Meetings between staffs and representatives are going well and quickly. but in the end, that doesn't matter".
Trump kept open the possibility of ensuing meetings with Kim following the one in Singapore, which he said will hopefully start "something big".
This would require a fundamental change in the nature of America's relations with North Korea and a move away from the system of division and confrontation within which the United States has dealt with Korea since the two Korean regimes were founded in 1948.
Mike Pompeo, Trump's secretary of state, has emphasized that the long-sought but elusive objective of "complete, verifiable, irreversible denuclearization" (CVID) continues to be the goal coming out of the summit.More news: Star Wars SHOCK: George Lucas ‘Fans would have HATED my sequel trilogy’
"The discussions between the United States and North Korea are ongoing and have moved more quickly than expected", the White House said in a statement.
Both Mr Trump and Kim have been trying to look as relaxed as they can before tomorrow morning's summit. USA officials scheduled to take part in Tuesday's expanded meeting will include Pompeo, Chief of Staff John Kelly, and National Security Adviser John Bolton.
The nuclear summit carries not just high stakes for the Korean Peninsula and the fate of millions, but also Trump's own political fortunes.
At the Panmun Souvenir Shop on the northern side of the demilitarized zone (DMZ) between the two Koreas, mere yards from where Kim and South Korean President Moon met in April, there is an extensive selection of propaganda posters and postcards decrying the "US Imperialists".
Such treats are unheard of for most North Koreans, even for government officials, who have seen their chances of overseas travel wither in recent years as their country's isolation has increased under sanctions imposed over its nuclear and missile programs.More news: Trump arrives in Singapore for summit with Kim
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