SEOUL—North Korea’s leader Kim Jong Un has fired an adroitly aimed missile right into the heart of the U.S.-South Korean relationship, putting the Americans on the defensive in the latest dramatic, unpredicted bid to warm over the hearts of Koreans.

By agreeing to the third North-South Korean summit, and the first ever at the truce village of Panmunjom 40 miles north of Seoul, Kim is not only stripping President Donald Trump of the “military option” of a preemptive strike against the North’s missile and nuclear facilities, but also raising questions about the wisdom of holding annual U.S.-South Korean war games as planned next month.

Trump put the best face on it in an uncharacteristically temperate tweet citing “possible progress” for “the first time in many years.”

Although South Korean conservatives accuse Kim of deceiving South Korea’s President Moon Jae-in by seeming to agree to Moon’s call for talks about denuclearization, the overwhelming sentiment here is in favor of keeping up the momentum for peace initiated during last month’s Winter Olympics in the South Korean resort district of Pyeongchang.

Moon and his aides clearly believe they have won a milestone victory in getting Kim to come more than halfway to meeting “the right conditions” that Moon said were needed before he could accept Kim’s invitation for a summit, which had come in a letter delivered personally by his younger sister Kim Yo Jong at the opening weekend of the Olympics.

Moon’s national security adviser, Chung Eui-yong, seemed almost jubilant as he briefed South Korean reporters Tuesday evening several hours after returning here from Pyongyang where Kim hosted him and other members of his delegation at a lavish dinner also attended by Kim Yo Jong and Kim’s wife, Ri Sol Ju.

Kim signaled his eagerness to come to terms that would please Moon and his aides by terming the conversation “open-hearted,” as quoted by North Korean state media.

The sense here, as conveyed by Chung, was that Kim Jong-un had agreed to virtually everything Moon wanted—and then some. The question, not asked but left hanging, was, “What more could we ask for?”

"The North side,” Chung said, “clearly affirmed its commitment to the denuclearization of the Korean Peninsula and said it would have no reason to possess nuclear weapons should the safety of its regime be guaranteed and military threats against North Korea removed.” Not only that, but “the North promised not to use not only nuclear weapons but also conventional weapons against the South.”

Weighing against the optimistic tone of these remarks, however, were memories of the disappointment of the two previous inter-Korean summits. In June 2000 the late Kim Dae-jung flew to Pyongyang to meet Kim Jong Il, the leader at the time, and the father of Kim Jong Un. But the “sunshine policy” faded abruptly as North Korea expanded its nuclear program. It carried out its first nuclear test in October 2006 a year before Kim Dae-jung’s successor, Roh Moo-hyun, also saw Kim Jong Il in Pyongyang in a failing bid to revive the spirit of reconciliation.

One crucial difference between those two summits and planning for the third summit is the agreement to hold it in Panmunjom, where the Korean War armistice was signed in 1953. The inference is that the two leaders will meet as equals, on neutral territory, in the Demilitarized Zone that has divided the two Koreas ever since.

Another hopeful sign was that Kim’s remarks, as relayed by Chung, were bereft of the anti-American venom routinely reflected in North Korean rhetoric, including Kim’s initial New Year’s speech in which he affirmed North Korean participation in the Winter Olympics while lambasting the U.S. as the North’s “real enemy.”

Some South Koreans, while welcoming the prospect of a North-South summit as the culmination of what many are calling the “Peace Olympics,” saw the timing of his show of goodwill as a skillfully contrived effort to force Moon to call for scaling down if not cancelling the war games that were to have been held in February, but were postponed until well after the Paralympics, which open Friday in Pyeongchang.

“ The two leaders will meet as equals, on neutral territory, in the Demilitarized Zone that has divided the two Koreas since 1953. ”

On the streets of Seoul, some Koreans expressed the view that Kim’s agenda also calls for getting Moon to advocate removal of the sanctions imposed by the U.N. and U.S. after North Korea’s nuclear and missile tests. Since Moon’s victory in the snap election for president last May, Kim has ordered 10 missile tests and North Korea’s seventh nuclear test.

(Moon was elected after the impeachment, ouster and jailing of his predecessor, Park Geun-hye, daughter of the dictatorial Park Chung-hee, who was assassinated by his own intelligence chief in 1979.)

As if to counter the criticism that South Korean conservatives were bound to voice, however, Chung reported that Kim had agreed on negotiations with the Americans on denuclearization—previously a taboo topic that the North said was not open for discussion.

“The denuclearization issue may be discussed as an agenda for the North-U.S. dialogue," said Chung. “We must especially pay attention” to the fact that Kim “clearly stated that the denuclearization of the Korean Peninsula was an instruction of his predecessor”—that is, Kim’s father, Kim Jong-Il, who died in 2011.

“There has been no change to such an instruction,” Kim was reported to have said, as if the entire nuclear crisis either had never happened or had been supremely unnecessary and could be relegated to history.

Moon was expected to report on the North-South talks in Pyongyang, the first such meeting in six years, in phone calls to U.S. President Donald Trump and also to Japan’s Prime Minister Shinzo Abe, who has been just as wary as the Americans of North Korea’s intentions.

Moon’s basic message is to be: Give peace a chance, let's see how the talks turn out before contemplating more steps to curb the North’s nuclear ambitions.

Moon will also be talking personally to Kim Jong Un before they meet in Panmunjom, said Chung, on a hotline set up “to allow close consultations and a reduction of military tension” in “the first phone conversation before the third South-North summit."