US President Donald Trump and North Korean leader Kim Jong Un begin their historic summit at 1pm NZT in Singapore, a meeting that could lead to peace between countries that have technically been at war for 68 years - or swiftly end in new recriminations.

Trump has said the public will be able to tell how the summit goes by what he says afterward. If he resumes talking about his "maximum pressure" campaign to squeeze Kim's regime, he said last week, "you'll know the negotiation did not do well."

Secretary of State Mike Pompeo said yesterday that "sanctions will increase" if talks don't move in the right direction. He told reporters that the discussions are "moving quite rapidly and we anticipate they will come to their logical conclusion even more quickly than we had anticipated."

It would've been hard to imagine the two leaders reaching this point just nine months ago. Trump labelled the North Korean leader "Little Rocket Man" in a speech to the UN General Assembly. Kim then called Trump a "mentally deranged US dotard" and a "frightened dog." They threatened each other with nuclear war.

The stakes remain dizzyingly high and the developments are likely to come rapid-fire. Here's a guide to the Trump-Kim summit:

What's the schedule?

Kim arrived on Sunday in Singapore, and Trump followed yesterday, after attending the G7 summit in Quebec.

Their first meeting will be at 1pm at the Capella Hotel, a five-star resort on Singapore's Sentosa Island - and a former pirate haunt. The two leaders will meet one-on-one before being joined by advisers, followed by a working lunch.

Trump has said the meeting could go one, two, or even three days. But the White House said that the President will hold a briefing at 8pm and then depart. One thing the American president said wouldn't make the schedule: a round of golf between the two leaders.

How we got here:

Kim announced late last year that his country had obtained the ability to strike the US with a nuclear weapon, and soon afterwards sought talks with South Korea on participating in the Winter Olympics. The moves defused immediate threats of military action by the US.

In March, Trump stunned the world by agreeing to meet Kim after South Korean officials told him that North Korea would suspend missile and nuclear tests, tolerate American military drills and move towards denuclearisation.

On May 10, Trump announced that he would meet Kim on June 12 in Singapore. Two weeks later, however, he cancelled the meeting in a letter to Kim, citing "open hostility" from North Korea. After he sat down with a senior adviser to the North Korean leader in the White House, Trump said on June 1 that the summit would take place as previously scheduled.

Advance teams from North Korea and the US have spent recent weeks in Singapore negotiating everything from presidential hotels to seating charts and lunch breaks during the summit.

What does Trump want?

Trump's goal is "ridding the US and the world of threats posed by North Korea's weapons of mass destruction and ballistic missile programmes," Secretary of State Mike Pompeo told reporters on June 7.

The US is also concerned about the proliferation of North Korea's weapons and the infrastructure supporting its nuclear programme, and will want those issues addressed as part of any deal. Trump is pushing for complete, verifiable, irreversible denuclearisation -- considered the gold standard among arms control experts.

Trump has also said he would raise the issue of Japanese citizens abducted by North Korea, after Japanese Prime Minister Shinzo Abe lobbied him in a meeting in Washington last week.

What does Kim want?

Kim likely will be eager to strike an agreement that eases sanctions and brings an end to the Korean War, while allowing him to keep at least part of his nuclear arsenal. He's pushing for "complete denuclearisation,'' which includes removing the US nuclear umbrella in Northeast Asia that protects allies South Korea and Japan.

Any framework agreement would likely require assurances that Kim could keep his grip on power even without nuclear weapons. South Korean President Moon Jae In said last month that Kim was worried he couldn't trust the US to guarantee his security if he gives up his nuclear weapons.

The summit itself provides a major propaganda win for the North Korean dictator, elevating him on the world stage to the level of the leader of the US. He will likely look to further end his country's isolation by increasing ties with China, South Korea, Russia and other nations.

How likely is a breakthrough agreement?

Experts are sceptical. At best, the meeting will likely provide a road map for future talks, each round of which will require difficult and complex negotiations. Most importantly, few believe Kim is actually willing to give up the nuclear weapons that cement his grip on power.

Further complicating the task ahead: Trump says he wants any eventual deal to earn congressional approval, providing more assurance to Kim, and reducing the risk a future US Administration would reverse whatever agreement he strikes.

There is a chance for some history, however. Trump has openly floated the possibility of striking a peace deal formally ending the Korean War 65 years after an armistice ceased military hostilities. Such an agreement could give talks some symbolic momentum and bolster leaders in both South and North Korea politically.

What's next

Following the meeting, Pompeo will travel to Beijing, Tokyo, and Seoul to brief regional powers on the talks.

The US has warned of a few surefire signs that the discussions aren't going well: if Trump decides to abruptly end the talks shortly after they begin, or if he emerges from the discussion by renewing his call for an international "maximum pressure" campaign.

The White House says it's already identified hundreds of additional sanctions targets if negotiations break down.

If things go well, South Korea's Moon may seek a trilateral summit with Trump and Kim on July 27 to mark the anniversary of the Korean War armistice signed on that day in 1953, according to South Korea's Chosun Ilbo newspaper.

Trump has also said he'd consider inviting Kim to Washington for a second round of talks.

- Bloomberg