By agreeing to a meeting between their leaders, the United States has already handed North Korea a long-sought diplomatic victory.
But could President Donald Trump's arguably reckless gamble open a path to resolving Washington's most dangerous foreign policy challenge?
Thursday's decision, which took the entire US foreign policy community by surprise, certainly shook up expectations.
Now, if Trump wants to ensure North Korea's peaceful disarmament, an extraordinary series of things will have to fall into place.
Washington has long insisted that it wants nothing short of the "complete, verifiable and irreversible denuclearization of the Korean peninsula."
Given the rapid progress in enrichment and weapons technology that Kim Jong Un's regime has made in recent years, that implies the North accepting a stern international inspection regime.
And, given that Washington and Pyongyang have no diplomatic relations and are technically only enjoying a truce in a war that began in 1950, it would also suggest the need for a peace treaty.
This in turn would mean the United States implicitly or explicitly recognizing Kim's maverick authoritarian regime, which has said it will not give up nuclear arms if it feels under US threat.
That is quite a diplomatic agenda.
"We've got to be properly prepared and we cannot underestimate Kim Jong Un. He's evolving into a strategic thinker, into a man with an end game," said veteran US politician and diplomat Bill Richardson.
"What we don't want to do is get trapped in a situation, a high-level negotiation where we're not prepared, where we don't have our best negotiators forward," Richardson, a North Korea expert, told CNN.
Perhaps the only comparable negotiation in recent history would be the one that led to the 2015 Iran nuclear deal and to Tehran opening up its nuclear program to international monitors.
But this was the fruit of 14 years of preliminary -- sometimes covert -- diplomacy followed by 20 months of intense negotiations involving senior diplomats from Iran and six world powers.
Trump's first meeting with Kim, if South Korean officials are to be believed, will come before the end of May -- less than 12 weeks away -- and Washington may not be ready.
For some of Trump's hawkish sympathizers in Washington, like Mark Dubowitz of the think tank the Foundation for Defense of Democracies, even the Iran talks outcome is a warning sign.
"The administration has to test this with a high bar to see whether North Korea is serious. If they are playing us, we should unleash maximum pressure," he said.
"The challenge is that the North Korea regime is a global champion, along with the Iranian regime, in playing us as fools."
Presumably, even if it was not consulted on Trump's impulse decision, the State Department would be involved in preparing a US negotiating strategy for the eventual summit.
But as late as Thursday afternoon, just two hours before Trump breathlessly warned White House reporters to expect a South Korean announcement, America's diplomats were in the dark.
Asked at 3:00 pm about the prospects for a meeting, a spokeswoman said: "We are not going to schedule talks about talks or any kind of chat or anything like that at this point."
Secretary of State Rex Tillerson was in Ethiopia when the news broke. Earlier in the day he too had played down hopes South Korea's outreach to the North would lead to a breakthrough.
If Trump or Tillerson had decided to consult serving US experts on the situation before the decision to talk was made, it's not immediately clear who they would have spoken to.
The United States special representative on North Korean policy, Joseph Yun, retired at the end of last week and no-one has yet been nominated to replace him.
Washington's contacts with Pyongyang are limited, but last year Yun successfully negotiated the return of a US prisoner, college student Otto Warmbier, from a northern jail.
He was a strong advocate for diplomatic engagement -- rather than threats of war -- in dealing with North Korea, but will not now be involved in what once seemed improbable talks.
Yun's boss in the State Department Bureau of East Asian and Pacific Affairs is respected China specialist Acting Assistant Secretary of State Susan Thornton.
Thornton is still "Acting" because she has yet to be confirmed in the job -- having been belatedly nominated after months of bitter wrangling over appointments between State and the White House.
Trump took his historic decision after meeting on Thursday in the White House with South Korean National Security Advisor Chung Eui-yong to hear second-hand about Kim's invitation to talks.
But America's ability to evaluate South Korea's strategy and advice may be hampered by the administration's failure to appoint an ambassador to Seoul, 13 months after taking office.
Until late last year, Korea expert Victor Cha of the Center for Strategic and International Studies, was strongly rumored to be the leading candidate for the ambassadorship.
This was not to be, but he nevertheless had advice and a warning for the administration Friday in a column in the New York Times.
"While the unpredictability of a meeting between these two unconventional leaders provides unique opportunities," he wrote, "its failure could also push the two countries to the brink of war."