The United States and North Korea have spent the past week scrambling to reschedule a June 12 summit between President Donald Trump and North Korean leader Kim Jong Un. If it takes place, it will be among the most memorable moments in recent US diplomatic history.

But what might actually happen if the two leaders meet? According to experts, there are four broad scenarios that could play out — each with vastly different and potentially dangerous consequences.

The first and most likely scenario is that Trump and Kim could agree to a broad framework for a nuclear deal at the meeting, and then allow their aides to work out the details over a longer period of time.

Second, the two leaders might agree to major concessions, like North Korea reducing its nuclear arsenal and the US removing troops from South Korea, but ultimately fall short of agreeing to dismantle Pyongyang’s entire nuclear program. That would still be a huge development, and possibly a diplomatic win for both sides.

Third, Trump and Kim agree to nothing. That would a scary outcome, as it would waste an opportunity to solve the nuclear standoff diplomatically — and may compel Trump and Kim to threaten war once again.

Finally, and by far the least likely option, North Korea acquiesces to Trump’s demands and agrees to completely dismantle its nuclear program.

This wide range of possible outcomes — from unlikely to practical to catastrophic — means the stakes for the Trump-Kim summit couldn’t be higher. After all, the reason they are talking is, in part, to avoid a horrific war.

Scenario one: small deal and more talks

This, experts tell me, is the most likely outcome of a Trump-Kim summit.

“What we should be expecting is ... a mutually agreed-upon outline for how the process moves forward, a sense of realistic timing, and some principles of what elements absolutely need to be included in an agreement from both sides,” Jenny Town, a Koreas expert at the Stimson Center, told me. “Then it gets handed down to negotiators to work out the details.”

In practice, this is the start of the deal. Trump and Kim would effectively be creating a road map for future negotiations, while offering up the usual diplomatic boilerplate.

That would still give staffers, like Secretary of State Mike Pompeo, a chance to find common ground. It’s possible that if both sides agree to more specific nuclear details down the line, Trump and Kim could meet again and finalize a more robust deal.

But neither leader will want to leave the meeting empty-handed, so they might offer up a symbolic concession to kick-start a much longer process. Trump could relax some of the tough sanctions placed on North Korea, and Pyongyang, meanwhile, might destroy some of its missiles — but not the ones that could reach the United States.

There would not be much to celebrate immediately, but it would hopefully serve as the beginning of a much grander opportunity for both countries to negotiate an end to the nuclear standoff — and avoid a horrific outcome.

Scenario two: big agreement without denuclearization

There is a chance — albeit small — that Trump and Kim agree to something quite dramatic.

Mintaro Oba, a former State Department official who focused on North Korea, told me that Pyongyang could agree to significant curbs on its nuclear program as long as the US offers something extraordinary in return. Here are two possibilities:

North Korea could agree to freeze or reduce its nuclear arsenal but not completely dismantle its entire weapons program. North Korea could agree to allow international inspectors to visit the country frequently to ensure it has stopped improving its nuclear and missile programs.

Either of those would be significant developments, since the country would be effectively decreasing its military power and reducing its threat to US allies like South Korea and Japan.

But what would the US have to do in exchange?

“I think it could be any combination of financial assistance, security guarantees, and a path toward normalization of relations,” says Oba. “I think the latter matters a lot to North Koreans, and they would welcome the establishment of liaison offices and more.”

That’s a crucial point: North Korea has long craved recognition from the United States. Sitting down with Trump makes North Korea look like a legitimate country. But establishing formal diplomatic ties with Washington, including sending a recognized ambassador to the US, would make it seem like a normal country in America’s eyes.

Of course, reaching that point would take significant time.

Trump could also agree to remove some of the 28,500 US troops in South Korea, something he has repeatedly said he wanted to do. Pyongyang sees those troops as a possible invading force, but Seoul considers them a security guarantee against a possible North Korean attack. To satisfy Kim and make some sort of deal, Trump may choose to harm the US-South Korea alliance.

Scenario three: no agreement

Let’s be clear: This would probably be the worst overall outcome.

Trump and Kim spent an inordinate amount of time in 2017 threatening to bomb one another. The current diplomatic gambit is, in part, to see if talks can solve the nuclear standoff instead of war. But if the talks fail, or either leader grows impatient with the process, both sides could return to threatening each other.

If Trump walks away from a summit or at least delays it, the chance of war increases slightly, Vipin Narang, a nuclear expert at MIT, told me. Trump already canceled the meeting once and continually says he will respectfully walk away from the summit if it doesn’t prove fruitful.

“But if Kim stands Trump up or there’s a dramatically bad interaction — which I highly doubt there will be — that empowers the hawks in the administration to say, ‘I told you so,’ and then all bets are off,” Narang continued.

Luckily, experts don’t think this outcome is likely. “If they really think they will come away with nothing, they won’t resume the summit,” Town told me. “There’s too much pressure on the situation now to have it just for show.”

So, as of this moment, it looks like Trump and Kim will avoid the worst.

Scenario four: North Korea agrees to denuclearize

Experts say there is basically zero chance Kim decides to completely dismantle his nuclear arsenal.

“Keep dreaming; it’s not going to happen,” says Narang. “They are not going to give us a peek at a subset, let alone all, of their nuclear weapons.”

Narang isn’t alone. Both the Pentagon and the CIA agree that North Korea sees its nuclear weapons as a deterrent from foreign invasion and therefore has no incentive to curb its nuclear program.

But South Korean President Moon Jae-in, who met with Kim last weekend, insists that Kim is willing to destroy his nuclear program. It’s unclear, though, if Kim actually said that, if Moon embellished the truth, or if Moon is just being too optimistic.

Moon, after all, has staked his political reputation on making a Trump-Kim summit happen, which explains why he rushed to North Korea to meet with Kim just two days after Trump canceled the summit last Thursday.

Trump, meanwhile, has staked a lot of his reputation on ending the North Korean nuclear threat. That menace doesn’t end until Kim no longer has nuclear weapons to launch. That means Trump may ask Kim to dismantle his program — and Kim will likely rebuff the president.

The main question is if Trump will accept nothing less than full North Korean denuclearization. If he can’t, then it’s unlikely he and Kim will find any common ground in Singapore. No one knows what would happen at that point, but war would remain a possibility.