US President Donald Trump is at Singapore's government house talking with the country's leader Lee Hsien Loong.
The two leaders were scheduled to meet one-on-one before an expanded working lunch with aides.
Earlier, North Korean state media confirmed that Kim Jong Un will discuss denuclearisation with Mr Trump at their Singapore summit.
KCNA said the pair would discuss a "permanent and durable peace-keeping mechanism" on the Korean Peninsula and other issues of mutual concern on Tuesday.
The report also said Mr Kim was accompanied by his foreign minister Ri Yong Ho, defence minister No Kwang Chol and his sister Kim Yo Jong.
Both parties have arrived in Singapore ahead of an historic coming together of Washington and Pyongyang.
The talks will be the first between a US and North Korean leader and will mark a sharp turnaround in the status of Mr Kim from international pariah to global player.
Just a few months ago, he and Mr Trump had been at loggerheads - trading insults and threats over Pyongyang's nuclear missile programme.
Asked by a reporter how he was feeling about the summit after touching down, Mr Trump said: "Very good."
Mr Trump arrived aboard Air Force One just a few hours after Mr Kim, who has only publicly left his country three times since taking power in 2011.
His visit to Singapore is his longest trip overseas as head of state.
Mr Kim met Singapore's prime minister shortly after landing and said Singapore's role would be recorded in history if the summit was a success.
North Korean leader Kim Jong Un meets with Singapore's Prime Minister Lee Hsien Loong | Image: Wong Maye-E/AP/Press Association Images
Mr Trump has said he will "know within a minute" if the North Korean leader is serious and soon after his arrival in Singapore, he wrote on Twitter: "Great to be in Singapore, excitement in the air!"
The White House has claimed credit for bringing Mr Kim to the table through a concerted campaign of tough economic sanctions, diplomatic efforts and the threat of military action.
Analysts believe Mr Kim's engagement is aimed at getting the US to ease crippling sanctions that have squeezed his poverty-stricken country.
He will also see a victory in having secured recognition and a seat at the negotiating table with the head of the world's leading superpower.
The on-off nature of the meeting means Singapore, which was chosen due to its history of holding high-profile summits and because it is seen as a secure location, has had just two full weeks to prepare.
G7 fallout
The US president flew there from a fractious G7 summit, which he threw into disarray after leaving by pulling out of an agreed communique and accusing Canadian Prime Minister Justin Trudeau of being "dishonest and weak".
On Sunday, German Chancellor Angela Merkel labelled Mr Trump's use of Twitter to withdraw from the G7 communique on trade "sobering and a bit depressing".
She also shared a photo on her Instagram account, which showed Mr Trump sitting with his arms crossed as Mrs Merkel and other leaders leaned over him.
Image: Instagram/bundeskanzlerin
Germany and France both issued robust responses to Mr Trump's decision to order US officials not to endorse the communique.
German foreign minister Heiko Maas posted on Twitter: "You can destroy an incredible amount of trust very quickly in a tweet.
"That makes it all the more important that Europe stands together and defends its interests even more offensively."
French President Emmanuel Macron's office issued a statement that warned "international co-operation cannot be dictated by fits of anger and throwaway remarks".
It added: "We spend two days working out a [joint] statement and commitments. We are sticking to them and whoever reneges on them is showing incoherence and inconsistency.
"Let's be serious and worthy of our people. We make commitments and keep them."
