SEOUL, South Korea — The first time South Korea hosted an Olympics — in 1988 in its capital, Seoul — the International Olympic Committee invited North Korea to talks in advance. The North Koreans showed up with a list of demands.
They not only insisted that half the events be held in Pyongyang, the North Korean capital, but they also wanted top billing, pressing for the Games to be renamed the Pyongyang-Seoul Summer Olympics, with the opening ceremony in Pyongyang. When South Korea said no, the North Koreans refused to attend.
“If one gives one finger to North Korea, they will take the whole hand,” the South Korean leader, Chun Doo-hwan, told I.O.C. President Juan Antonio Samaranch in 1986.
It’s a different picture three decades later, as South Korea prepares to host its second Olympics. The North Koreans are not only joining, their athletes will also march with the South Koreans in the opening ceremony and compete side by side in the Koreas’ first joint Olympic team, in women’s ice hockey.
The turnaround underscores the changed role that the Olympics have come to play in the tense relations between the two Koreas, which never signed a peace treaty to end the 1950-53 Korean War. For years, the rival Koreas used the Games to showcase their competing claims to represent the Korean people, and try to one up each other.
More recently, however, the North and South have come to see international sporting events as a chance to defuse tensions, including the current standoff over North Korea’s nuclear weapons and ballistic missile programs. The two Koreas have also learned to use Olympic diplomacy to achieve in a small, symbolic way a much bigger goal that eludes them in the real world: a show of unity across the divided Korean Peninsula.
“It is not an impossible dream,” South Korea’s president, Moon Jae-in, said at the United Nations in September. He said the coming Olympics, which are being held in the South Korean resort of Pyeongchang, “will become a candle that sheds light on peace.”
Even the limited show of cooperation during the Pyeongchang Olympics is the culmination of a long process of sports rapprochement that has tracked the ups and downs of the larger political relationship between the two Koreas. No evidence has surfaced of the wealthy South paying off its impoverished neighbor in exchange for Olympic cooperation, but the advances have come at times when the South was more forthcoming with aid and investment.
Last year, the administration of Mr. Moon offered to donate $8 million to two United Nations humanitarian programs working in North Korea. Mr. Moon suspended the plan after international pushback that the offer might undermine United Nations sanctions against the North’s nuclear weapons and missile programs.
In Pyeongchang, South Korea will pay for the joint uniforms to be worn by athletes of both sides during the opening ceremony, and foot the bill for housing and feeding hundreds of North Korean dancers and cultural entertainers who will perform during the Games. However, no money will go directly to them, South Korean officials have said.
The North Koreans are also likely to be the only athletes not to receive a free smartphone from the Olympic sponsor Samsung. South Korean officials said they were keen to dispel concerns, particularly in Washington, that they were making payments to the North that could violate sanctions.
“We are trying to brief the Americans so thoroughly about every detail of matters concerning sanctions and the North Korean delegation that they get tired of hearing it,” said Cho Myoung-gyon, who as South Korea’s unification minister is in charge of dealings with the North.
The I.O.C. first urged North and South Korean sports officials to meet in 1963, a time when East and West Germany had created a joint Olympic squad. But the two Koreas could get no further than deciding that a hypothetical joint squad would use a well-known Korean folk song, “Arirang,” instead of picking one of their national anthems.
They agreed to talk again before the Los Angeles Olympics in 1984. But when they met on their shared border, the heavily fortified demilitarized zone, the talks quickly devolved into mutual recriminations. South Korea demanded that the North apologize for its bombing of Mr. Chun’s presidential delegation in Burma the previous year, which killed 17 South Koreans, while North Korea called Mr. Chun a “bloody-handed” dictator for ordering the massacre of protesters in the city of Kwangju in 1980.
“It was nothing but a slandering match,” said Lim Tae-sun, 83, a former South Korean negotiator who was present at the meeting. “We hardly discussed the real agenda.”
In 1985, the I.O.C. invited the two Koreas to Lausanne, Switzerland, in an attempt to broker an end to North Korea’s bitter campaign against the 1988 Summer Games awarded to Seoul. The North insisted on sharing the Games, arguing that “hosting of the Games by one part of the nation aggravated the antagonism and division between the two peoples.”
It also made veiled threats, telling a visiting I.O.C. vice president that “any accidental error would have disastrous effects on the peaceful celebration of the Games.”
South Korea countered by offering only a few events, like table tennis and archery, to the North. When North Korea boycotted the 1988 Games, only a handful of its allies, including Cuba, followed suit.
The first breakthrough came at the end of the Cold War, when the two Koreas agreed in 1991 to form a joint team for the World Table Tennis Championships in Chiba, Japan.
Under the deal, the two governments agreed that the unified team would use the name Korea, and carry a blue-and-white flag showing an undivided Korean Peninsula. The South also made a key concession, agreeing that each Korea should contribute the same number of players.
The brief sports détente came to an abrupt end that same year when a North Korean attending a judo championship in Barcelona, Spain, defected to South Korea. The North receded into deeper isolation during a devastating famine.
In the late 1990s, South Korea persuaded the North to resume sports exchanges with the help of economic aid from a private citizen, Chung Ju-yung, the billionaire founder of South Korea’s Hyundai conglomerate. In 1999, the two Koreas played friendly basketball matches in Pyongyang and Seoul after ground was broken for an arena Mr. Chung donated in the North Korean capital.
Sports exchanges flourished as the two Koreas achieved a political rapprochement during the early 2000s, when liberal administrations in South Korea pursued a Sunshine Policy of promoting warmer ties backed by generous offers of aid and investment. The two Koreas marched together in the Olympic opening ceremonies in 2000, 2004 and 2006.
But even during these years, a joint Olympic team remained out of reach. South Korean athletes objected to relinquishing their hard-won spots. Coaches said the two Koreas remained just too far apart in thinking, training and abilities.
“I find it hard to imagine archers from the two Koreas competing on the same team,” Seo Keo-won, an executive at the Korea Archery Association in Seoul, said at the time.
The sports diplomacy froze in 2008 as a new conservative government in Seoul limited ties with the North, refusing to turn a blind eye to its weapons programs. Talks to field a joint team at the Summer Games that year in Beijing collapsed after the South rejected the North’s condition of equal numbers of athletes.
This year’s deal came after Mr. Moon, a political liberal who has expressed eagerness to restore inter-Korean exchanges, took office last May. The North also showed flexibility in agreeing to a joint squad in women’s hockey, one of the few winter team sports in which it competes.
The joint team was created by adding 12 North Koreans to the existing South Korean national team of 23 players. The head coach is a Canadian appointed by South Korea, who must select at least three North Koreans to play in each game.
South Korean officials say they did not promise aid for the deal. But they did make one important concession: postponing joint military exercises with the United States.
“Sports exchanges can prosper only when political issues are resolved,” said Chang Ung, a North Korean member of the I.O.C., after landing in Seoul this week. “That is an unbreakable rule on the divided Korean Peninsula.”