Sometime after 9 am on June 12, at the swank Capella Hotel on Singapore’s Sentosa Island, President Donald Trump will shake hands with Chairman Kim Jong-un, the youthful dictator of North Korea. Their symbolic gesture will shatter decades of hostility between the United States and the communist state and—if all goes well—usher in a new era of peace in Korea and Northeast Asia.

“The summit is all ready to go,” Trump announced Thursday at the White House. “We’ve been preparing for a long time.” He said the summit meetings will be “very fruitful,” but must end with Kim agreeing to disarm. “They have to de-nuke,” he insisted. “If they don’t denuclearize, that will not be acceptable.”

The unprecedented meeting is the direct result of a diplomatic initiative Kim launched in January with South Korean President Moon Jae-in. It culminated on April 27 with a joint declaration to end “the Cold War relic of division and confrontation” through the “complete denuclearization” of the Korean peninsula. In March, Kim’s offer to meet Trump was conveyed by senior South Korean officials, making Moon a mediator between Washington and Kim’s government in Pyongyang.

“This isn’t a charm offensive, this isn’t some sort of tactical trick,” Joel Wit, a former US negotiator with North Korea, said in response to critics who claim Trump and Moon are being “played” by Kim Jong-un. “There is enormous momentum in Pyongyang behind what they’re doing.” Wit, who is a senior fellow and director of 38 North, a research institute in Washington, spoke this week at a press briefing sponsored by the Stimson Center.

A likely outcome of the Trump-Kim encounter—which is already being called “the summit of the century”—is a joint declaration ending the state of war and transforming the 1953 armistice that ended the fighting into a permanent peace treaty. That would set the stage for an agreement to end North Korea’s nuclear-weapons and ballistic-missile programs, which the United States has viewed for years as a strategic threat. “We could sign an agreement” to end the war, Trump said Thursday. “We’re looking at it.”

For the summit to be a success, however, the Trump administration expects North Korea to announce a firm timetable for disarmament and publicly commit to an international system of verification. In return, Washington is apparently prepared to lift economic sanctions and agree to the full normalization of political and economic relations that North Korea has long sought with the United States.

“The President recognizes that North Korea has great potential, and he looks forward to a day when sanctions on the [North] can begin to be removed,” Secretary of State Mike Pompeo told reporters at the White House Thursday. “However, that cannot happen until [North Korea] completely and verifiably eliminates its weapons of mass destruction programs.” Once it does, he said last week, “We envision a strong, connected, and secure, prosperous North Korea that maintains its cultural heritage but is integrated into the community of nations.”

The possibilities of a peace agreement, and the benefits it would bring to both sides of the Demilitarized Zone, have captivated Koreans all over the world. “It’s time to declare an end to the Korean War and replace the armistice with a peace treaty to build a stable and lasting peace system on the Korean Peninsula,” a coalition of Korean American groups said in a joint “statement of unity” published on Thursday. “Only a peace treaty will prevent further threats of nuclear and conventional war on the Korean Peninsula.”

But Trump’s decision to meet with Kim has been greeted with skepticism and even derision in some quarters of the US foreign-policy establishment. On June 4, Senate minority leader Chuck Schumer (D-NY) issued a harsh letter to Trump indicating that the president could face serious opposition in Congress if he offers concessions before North Korea shows that it has ended its nuclear and missile program.

The letter—signed by seven leading Democrats, including Senators Sherrod Brown of Ohio and Patrick Leahy of Vermont—demands that North Korea dismantle and remove “all [its] nuclear, chemical, and biological weapons” before getting anything in return. “Any deal that explicitly or implicitly gives North Korea sanctions relief for anything other than the verifiable performance of its obligations to dismantle its nuclear and missile arsenal is a bad deal,” the senators wrote.

Hankyoreh, South Korea’s only progressive daily, expressed shock at the letter’s hostile tone. “These are largely the same as the demands made by US National Security Advisor John Bolton and other hard-liners in the Trump administration,” it noted, correctly. The Democrats’ preemptive and pointed antipathy toward Trump’s potential settlement seems an indication that he may face congressional opposition to any agreement that could be reached in Singapore—ominously mirroring what happened to President Clinton’s Agreed Framework in 1994, under which the North froze its nuclear-development program for nearly 12 years.

But many Americans with expertise in diplomacy and North Korean strategy applaud Trump’s moves. “I really think this is a big deal, and I don’t think they’re getting enough credit for the fact that the administration and the president have up-ended this whole notion that engagement with an adversary is a reward and it should be avoided at all costs,” Suzanne DiMaggio, a negotiator who meets regularly with North Korean diplomats, told a media briefing this week in Washington.

“Instead, they’ve made it clear that meeting with an adversary, probably our greatest adversary at the moment, at least in the president’s mind, is not viewed as a concession,” said DiMaggio, who was the subject of a Nation profile last year. “So, this is a welcome turn to diplomacy, to resolve the whole range of issues we have with Pyongyang.”

The outcome, however, is far from certain. Despite strong statements of intent from both sides to resolve their 70-year standoff, there is still a considerable gap between the US demands for Kim to rapidly disarm and North Korea’s desire for an end to what it defines as America’s “hostile policy.”

To the North, that policy encompasses the US nuclear weapons carried on its armada of warships and bombers in the Asia region; the biting sanctions imposed on North Korea that threaten Kim’s desire to shift from military spending to the economy; and annual military exercises in which US and South Korea forces train for contingencies such as a retaliatory invasion of North Korea.

Moreover, getting here hasn’t been easy. Two weeks ago, Trump angrily canceled the summit after a scathing North Korean attack on Bolton and Vice President Mike Pence for proposing a Libya-style denuclearization plan that the North sees as a thinly disguised pitch for regime change. But the summit was quickly rescheduled after Kim Kye Gwan, North Korea’s vice minister of foreign affairs, issued a conciliatory statement to Trump and Chairman Kim, in a hastily called meeting with Moon, pledged again his desire for denuclearization.

But, in a sign of the deep division inside the administration, CNN reported on June 5 that State Department officials now believe that Bolton, with his Libya comments, was trying to “deliberately disrupt” the North Korea talks. According to the Los Angeles Times, Trump “told associates in private that he was furious with Bolton for his choice of words and blamed him for spooking the North Koreans.”

With the hard-liners possibly out of the way, Trump now has a chance to accomplish what no other US president has been able to do for over three decades: convince North Korea to permanently end its nuclear weapons program by forging a new diplomatic relationship with the same country the United States nearly destroyed during the Korean War. That violent history seems to have grabbed the president’s imagination, and driven some of his interest in changing it going forward.

“You’re talking about years of hostility; years of problems; years of, really, hatred,” he declared last week after meeting at the White House with Kim Yong-chol, North Korean President Kim’s top adviser and a former spy chief.

Not surprisingly, Bolton wasn’t at that meeting—an early hint of Trump’s unhappiness with his national-security adviser (Bolton will be in Singapore, however, along with Chief of Staff John Kelly, and Secretary of State Pompeo. Also expected there, according to Bloomberg, will be Andrew Kim, the CIA’s top expert on Korea, and Allison Hooker of the National Security Council, who have both had extensive interactions with the Kim government in summit preparations).

Trump’s meeting with Kim Yong-chol marked the first time in 18 years that a senior North Korean official was allowed to visit Washington. For the previous two days, he’d been in New York hammering out final details for the summit with Pompeo, who has now visited Pyongyang twice. Afterwards, Pompeo spelled out clearly what he and Trump would seek to accomplish. “The United States objective is very consistent and well known: the complete, verifiable, and irreversible denuclearization of the Korean Peninsula,” he said.

Those meetings brought the two governments together on one point: Both have scaled back expectations from a “big bang” approach, where the entire agreement would be signed, sealed, and delivered before the two leaders went home to their respective capitals. Instead, they jointly view Singapore as the start of a protracted series of negotiations ending, in the US view, with a final agreement on denuclearization.

The summit “will be a beginning,” Trump told reporters last week. “I’ve never said it happens in one meeting.” There is also talk of a follow-up summit, perhaps in Mar-a-Lago in Florida. (“I think it would be well-received,” Trump said on Thursday. “I think he will look at it very favorably.”)

North Korea has also expressed a strong desire for a step-by-step process. “The first meeting [with Trump] would not solve all, but solving even one at a time in a phased way would make the relations get better rather than making them get worse,” North Korea’s Kim Kye Gwan said in the May 25 statement that put the summit back on track.

Ambassador Robert Gallucci, who was the chief US negotiator with North Korea in 1994, agreed with this process at the 38 North briefing this week. “Those of us who have been involved in negotiations know everything doesn’t happen all at once,” he said. “It’s going to happen over a period of time.”

But this step-by-step approach—which is strongly endorsed by President Moon—has drawn sharp criticism from Washington hawks. For the most part, the think-tank intelligentsia and North Korea “experts” believe that an agreement to end the war would be premature if it comes before Kim Jong-un has completely, and irreversibly, denuclearized.

The most prominent of those critics has been Victor Cha of the Center for Strategic and International Studies—the man Trump almost appointed to be US ambassador to South Korea just a few months ago. Cha set his preferred tone on June 1, tweeting that South Koreans “are moving too fast” on a peace treaty and are thus “trying to box US in.” He repeated this idea on Tuesday morning in testimony before Congress, and his line that a peace agreement is premature without denuclearization was echoed on several of last Sunday’s talk shows.

On CBS, Jung Pak, a Korean-American former CIA officer who analyzes North Korea for the Brookings Institution, described a peace agreement as a “shiny object” that should not be the focus of the initial talks. “We have to remember that we can’t have peace on the Korean Peninsula without denuclearization of North Korea, and that peace without denuclearization is going to be a fake peace,” she said on Face the Nation.

But DiMaggio, who knows the North Koreans well, said it’s important for the United States to understand the views of people who inhabit the divided country.

“I’m always amazed by the pushback to a peace treaty,” she told The Nation on Thursday. “It’s what the Korean people want. The idea of a declaration, publicly together, ending the war” is “not a major concession,” she said. The memories of the war for the North Korean diplomats she knows are visceral, she added. “It consumes them. This is a war they have continued to live.”

The Ploughshares Fund, the peace group that sponsored DiMaggio’s briefing, urged the administration to take a long-term approach to North Korea. The summit “would be a success if North Korea agrees to eventual, phased denuclearization in exchange for phased economic, political and security incentives,” the organization said a statement released Thursday afternoon.

“Complete denuclearization will take time,” Ploughshares continued, “the physical process of eliminating the North’s nuclear and missile arsenal and infrastructure would take years, as would the political process of building the necessary confidence between the parties. All told, this process may take five years or more.”

Given the impatience in Washington with Trump’s policies, that could be a tall order. But whatever Trump and Kim decide in Singapore, the highest-level talks in US-North Korean history will be a milestone for two countries that have been locked in conflict since North Korea was founded as a separate state in 1948. Democratic hawks and think-tank militants may not like that engagement process, but many Americans, along with millions of people in Korea and around the world, are breathing a sigh of relief that the talks are happening at all.