US President Donald Trump and North Korean leader Kim Jong-un meet for an unprecedented summit aimed at defusing tensions on the Korean peninsula.
No sitting US president has ever met a North Korean leader.
Mr Trump has said the highly anticipated talks represent a "one-time shot" at peace.
The meeting marks a dramatic shift in relations between the pair, who last year traded insults and threats of war.
Washington hopes the summit will kick-start a process that eventually leads to denuclearisation of the Korean peninsula.
North Korea has said it is willing to commit to denuclearisation, but it is unclear how this will be achieved or what might be requested in return.
The summit will be held at a hotel on Sentosa, a popular tourist island a few hundred metres off the Singapore mainland, at 09:00 local time (1pm NZT).
Heavy security and armed police are standing guard at summit-related venues across the city state.
The two leaders are staying in separate hotels, not far from each other.
In his latest tweet, hours before the summit was due to begin, Mr Trump said meetings between the two sides' officials were "going well and quickly".
He continued: "But in the end, that doesn't matter. We will all know soon whether or not a real deal, unlike those of the past, can happen!"
Mr Kim spent the evening before the meeting visiting some of Singapore's tourist sites.
He smiled and waved to excited crowds and was accompanied by Singapore's foreign minister, who tweeted a selfie standing next to him.
Why is this remarkable?
For decades, North Korea has been a pariah state, and now its latest hereditary leader is being treated as a world statesman.
Last year, it would have been a rare sight to see a North Korean flag flying anywhere in Asia.
Now, Mr Kim - who runs a totalitarian regime with extreme censorship and forced-labour camps - is meeting and greeting dignitaries.
"The circus-like atmosphere might be amusing if the stakes weren't so high," wrote US campaigning group Human Rights Watch.
What is the agenda?
New details of the agenda have been released.
According to the White House, this is the plan for the summit:
- Mr Trump and Mr Kim initial greetings (09:00 local time; 1pm NZT)
- One-to-one meeting
- Expanded meeting with other representatives
- Working lunch
Mr Trump will leave the country that same evening to return to the US. Mr Kim is reported to be flying out even earlier, at 14:00 local time (6pm NZT).
What are the talks about?
The talks will focus on North Korea's controversial nuclear programme.
"They have to de-nuke. If they don't denuclearise, that will not be acceptable," Mr Trump said ahead of the meeting.
US Secretary of State Mike Pompeo said the US would only accept "complete, verifiable and irreversible denuclearisation" - but would offer "unique" security guarantees, that would provide North Korea with "certainty... that denuclearisation is not something that ends badly for them".
A formal end to the Korean war may also be discussed. The 1950-53 conflict ended with a truce, not a final peace treaty. Mr Trump says signing a peace agreement would probably be "the easy part".
How did we get here?
A sit-down with the US president is something North Korea has long pushed for.
It is an outcome that seemed unimaginable less than a year ago - when Mr Trump and Mr Kim exchanged streams of fiery insults - and North Korea conducted several ballistic missile tests in defiance of the international community.
Mr Trump famously vowed to unleash "fire and fury" if Pyongyang kept threatening the US. Meanwhile, Mr Kim has called Mr Trump "mentally deranged" and a "dotard".
Previous attempts to negotiate with Pyongyang have failed, but earlier this year North Korea demonstrated a new openness to diplomacy and held direct talks with Seoul.
The rapid improvement in relations between the North and South Korea - technically still at war - culminated with a historic leaders' summit in April.
During this warming of relations between the two Koreas, March saw Mr Trump stun the world by accepting an invitation to meet Mr Kim.
Still, the road to the Singapore talks has been far from smooth.
The lead-up to the summit has been marked by uncertainty and waves of frenetic diplomacy - at one point, Mr Trump even briefly called off the summit, after a senior North Korean official described remarks by US Vice-President Mike Pence as "stupid".
Talks of this kind typically take months to prepare. Critics fear that Mr Trump is poorly prepared for the negotiations - while others say Mr Trump's quickfire approach has already produced results - including North Korea saying it is willing to consider denuclearising.
What do both sides want?
The US wants North Korea to get rid of its nuclear weapons in an irreversible manner that can be verified by the international community.
But analysts question why Mr Kim would give up his nuclear weapons after pushing so hard to get them. They also say by winning the prestige of a meeting with the world's most powerful leader, Mr Kim has already gained a victory.
The North Korean leader has also said he now wants to focus on building the country's economy - and wants sanctions relief and international investment.
Still, the US is not expecting a final deal in Singapore. President Trump has described it as a "get-to-know-you situation" and said "it's going to be a process".
The US president has also said that if he thinks things are going badly, he will walk out of the meeting, but if things go well, Mr Kim could receive an invitation to the White House.