The most hotly anticipated geopolitical summit in years will put President Donald Trump across the negotiating table from dictator Kim Jong Un.
It will be the first time a sitting U.S. president has met with the leader of North Korea, which is perhaps the world's most reclusive and repressive nation. Mutual mistrust between Washington and Pyongyang has already seen the meeting canceled and hastily reinstated days later.
But symbolism aside, what, if anything, might be agreed when both men emerge from their face-to-face meeting in Singapore on Tuesday?
Andrea Berger, a senior research associate at the Middlebury Institute of International Studies at Monterey, California, said there is "a fairly wide spectrum of potential outcomes from the summit."
These range "from a breakdown of the meeting or a limited joint statement, to some implausibly ambitious plan for North Korean disarmament and transformation of the Korean Peninsula security situation," she added.
In a perfect world for Trump and his team, Kim would agree to the "complete, verifiable, irreversible dismantlement" of North Korea's nuclear program.
This goal — often referred to by the acronym CVID — has been Washington's stated aim for much of the run-up to the talks.
But most experts say it's highly unlikely that this will happen quickly, if ever.
"It is simple, but improbable," says Andrei Lankov, a professor at Kookmin University in Seoul and the director of the NK News website.
In this far-fetched scenario, Lankov says, "Kim Jong Un accepts CVID and then immediately starts to ship all his nuclear weapons, as well as crucial equipment, to the U.S. or third countries."
The problem is that North Korea sees its nuclear weapons as an invaluable insurance policy against the U.S. invading and attempting to topple the Kim dynasty.
Convincing Kim to trust the West and give up his nuclear weapons entirely would be difficult. He has seen Saddam Hussein in Iraq and Moammar Gadhafi in Libya both abandon their WMD progams only to be toppled anyway.
The specter of Libya almost derailed the Singapore summit after its history was used as an example by National Security Adviser John Bolton.
Inderjeet Parmar, a professor of international politics at City, University of London, went as far as to say that "Trump's goal of totally de-nuking North Korea is impossible."
The CIA agrees.
Even Trump himself appeared to water down expectations last month.
"It's a process," he told reporters. "We're not going to go in and sign something on June 12, and we never were."
What makes this a particularly high-stakes summit is the potential price of failure.
Not only could Trump and Kim fail to make progress, their relationship could deteriorate fast and take the region with it.
"Worst case is that the two leaders backslide into the exchange of personal insults," said Robert Kelly, professor of political science and diplomacy at Pusan National University in South Korea.
Some analysts worry about the unpredictability of putting Trump, a man never shy of speaking his mind, in the same room as Kim, a young, ruthless autocrat who has killed members of his own family to consolidate his grip on power.
Lankov, the professor at Kookmin University, imagined how things could go wrong.
"No compromise is reached, one of the two major participants storms out of room, and tensions began to mount again, resulting in a military conflict at some point next year," he said.
A third way
Many experts feel the outcome of the summit will be something rather more mundane.
"The realistic best case is a summit meeting that happens on schedule, doesn't break up early, and delivers a joint statement," according to Joshua H. Pollack, who is also a senior research associate at the Middlebury Institute of International Studies at Monterey.
Pollack believes the risk of summit meltdown was reduced with the diplomatic toing and froing that accompanied its cancellation and subsequent reinstatement.
"This episode seems to have helped to acquaint the two sides with each other's positions, as opposed to their wishful thinking about each other, and reduced everyone's expectations for the meeting to something more realistic," he said.
While few expect full CVID, the North could agree to an official stop of weapons tests, and later a partial surrender of its nuclear weapons and related material and equipment.
The two sides could also agree to hold further talks, building a road map to eventual denuclearization — although they may still disagree on what "denuclearization" actually means.
In return, the U.S. might agree to curb certain aspects of the military drills it holds with South Korea, and eventually even lift some sanctions against Kim's regime.
These commitments would be largely "old wine in new bottles," as Pollack puts it, but more important they could "kick off a more systematic, working-level diplomatic process that may accomplish something substantive, if given the time."
Even if the North agrees to denuclearization but then does everything it can to frustrate the process, as many predict it would, an agreement alone might be better than nothing.
"Such an imperfect compromise deal will dramatically decrease the level of the North Korean threat, and thus should be welcomed," Lankov said.
Kelly, at Pusan National University, is more skeptical.
"Likely outcome is a nothingburger," he said. "A weak-tea statement with some photos, which embarrass the U.S. by showing Trump jovially engaging the world’s worst human-rights abuser for nothing."