By Choe Sang-Hun, New York Times–

President Moon Jae-in of South Korea was greeted by throngs of North Koreans shouting “Reunification of the fatherland!” as he arrived in the North on Tuesday on a high-stakes mission to persuade its leader, Kim Jong-un, to commit to startdismantling his nuclear weapons program.

Mr. Moon is holding his third summit meeting with Mr. Kim, a three-day visit during which the two will discuss improving inter-Korean ties and easing tensions along their countries’ border, the most militarized in the world. It was Mr. Moon’s first visit to Pyongyang as South Korea’s leader, and it comes after the two met on the border in April and May.

The big question hovering over the talks is whether Mr. Kim will agree to take steps to convince Washington that he is willing to denuclearize. American officials want to see concrete steps from the North, including submitting a full list of its nuclear weapons and facilities and fissile materials, and they want it to freeze its nuclear activities.

Mr. Kim expressed optimism on Tuesday about the future of the negotiations, thanking Mr. Moon for helping bring about his June summit meeting with President Trump in Singapore.

“Thanks to that meeting, the situation around the Korean Peninsula has stabilized, and we can now expect more progress,” Mr. Kim said at the start of a two-hour meeting with Mr. Moon at the headquarters of the ruling Workers’ Party, according to pool reports from South Korean journalists in Pyongyang, the North’s capital.

Mr. Kim greeted Mr. Moon on Tuesday morning at the Pyongyang airport, kicking off a spectacle that stressed the ethnic affinity of the two Koreas, while giving few clues to whether he is willing to give up his nuclear weapons.

When Mr. Moon stepped off his plane, a smiling Mr. Kim was waiting on the tarmac with a military honor guard and a large crowd of Pyongyang citizens mobilized for his arrival. After the two leaders hugged each other and moved to their cars, the crowd fervently chanted “Hurrah!” and “Peace and prosperity!” while waving plastic flowers and “Korea-is-one” flags that showed an undivided Korean Peninsula.

As the motorcade carrying Mr. Moon and Mr. Kim to a state guesthouse wove through Pyongyang, huge crowds, mostly women clad in bright flowing dresses, lined the boulevard, waving pink flowers and chanting for reunification.

Over the years, the North’s propaganda toward the South has mostly focused on ridiculing it as an “American running dog.” But when it seeks warmer ties with the South, it also stresses the ethnic affinity of the two nations.

Tuesday’s crowds were clearly mobilized to demonstrate the North Koreans’ adoration for Mr. Kim and their support for his uriminzokkiri, or “among our nation,” policy of stressing inter-Korean cooperation while the North engages in a nuclear standoff with the Americans.

The highly choreographed crowds like those seen Tuesday remain a regular phenomenon in North Korea, where the state routinely mobilizes the populace as a way of keeping them loyal and disciplined, analysts say.

The motorcade passed major landmarks of Pyongyang: the Tower of Eternal Life, which honors Mr. Kim’s late grandfather and father, who ruled before him; Ryomyong Street, lined with pastel-colored skyscrapers built as Mr. Kim’s signature project; and the Kumsusan Palace of the Sun, where the late Kims lie in state inside glass boxes.

Behind the spectacle, South Korean analysts warned that much was at stake in Mr. Moon’s efforts to mediate a breakthrough in the stalled dialogue between Washington and Pyongyang. If he fails to coax Mr. Trump and Mr. Kim to hold a second summit meeting, the Korean Peninsula might revert to the roiling tensions that put the region on the brink of war last year.

South Korean President Moon Jae-in and North Korean leader Kim Jong Un wave during a car parade in Pyongyang, North Korea, September 18, 2018. Pyeongyang Press Corps/Pool via REUTERS© Pyeongyang Press Corps/Pool via REUTERS South Korean President Moon Jae-in and North Korean leader Kim Jong Un wave during a car parade in Pyongyang, North Korea, September 18, 2018. Pyeongyang Press Corps/Pool via REUTERS

When Mr. Moon’s special envoys visited Mr. Kim in Pyongyang early this month, he told them that he was willing to denuclearize within Mr. Trump’s first term. But he said he would start taking phased actions toward that goal only if Washington reciprocated with “simultaneous” measures to prove that it was no longer hostile, the envoys said. At the same time, the North is continuing to expand its nuclear arsenal.

As a first step, the North wants the United States to declare an end to the 1950-53 Korean War. The war was halted in a truce, not formally with a peace treaty, 65 years ago, leaving the peninsula still technically at war.

Mr. Moon and Mr. Kim were scheduled to announce the results of their meetings on Wednesday.

Next week, Mr. Moon is expected to brief Mr. Trump during a trip to the United Nations. Then, Mr. Trump is expected to decide whether he will meet with Mr. Kim again. The White House said last week that Mr. Kim had recently proposed a second meeting.

“If my visit helps restart North Korea-U.S. dialogue, that itself will be highly meaningful,” Mr. Moon said on Tuesday.

On Tuesday morning, North Korea’s state media told its people of Mr. Moon’s planned visit, saying that his meeting with Mr. Kim “will offer an important opportunity in further accelerating the development of inter-Korean relations that is making a new history.” It did not make any reference to its nuclear weapons program.

The stakes are high for Mr. Moon.

Mr. Moon has dedicated his country’s diplomacy to brokering dialogue between North Korea and the United States after the two nations appeared on a collision course last year, with Mr. Kim accelerating his missile and nuclear tests and Mr. Trump threatening to rain “fire and fury” on the North.

Senator Lindsey Graham of South Carolina, a member of the Senate Armed Services Committee, said on Sunday that “there was a point in time” when Mr. Trump seriously discussed pulling American military dependents out of South Korea — a move that would have been widely seen as a precursor to military action on the peninsula. Mr. Graham warned that the current lull in tensions would not last if Mr. Trump determined that Mr. Kim was “playing” him.

“This is the last best chance for peace right here,” Mr. Graham said on CBS’s “Face the Nation. “If he has to, he’ll use military force to stop a missile coming to America with a nuclear weapon on it originating in North Korea.”