Mr. Ri arrived in Sweden on Thursday for the talks, which had been long planned but gained widespread attention after Mr. Trump accepted Mr. Kim’s invitation.

Mr. Lofven said this month that he was willing to host a meeting between Mr. Trump and Mr. Kim. “If we can help in any way, we will do it,” he said at a news conference, noting that Sweden has had an embassy in Pyongyang since the 1970s.

“Their trust in us is longstanding because we were first on the spot. We were the ones to break the ice and open an embassy,” said Erik Cornell, the Swedish ambassador who opened the country’s embassy in Pyongyang in 1975.

Niklas Swanstrom, the director of the Institute for Security and Development Policy, a Swedish research group, said the country has “had some access and influence in North Korea.”

“Comparative to other Western states, we have had a unique relationship with the North Korean government, due to our neutrality, due to our supervisory role and also the protective mission,” said Mr. Swanstrom, referring to Sweden’s supervisory role in monitoring the armistice that ended hostilities in the Korean War.

If the upcoming talks were to be held in a foreign country, then Sweden or Switzerland could be an option, Mr. Swanstrom said, but added that it was more likely they would take place in the Korean Demilitarized Zone. “The DMZ is more likely, as Mr. Kim has not traveled outside the country since he took power,” Mr. Swanstrom said.

On Friday, in a short statement to journalists, Ms. Wallstrom said, “We are glad that we can have this meeting.” She added: “But we are not naïve in any way. We do not think that we can solve this issue. It is up to the parties to solve it. If we can use our contacts in the best way, then we will do that.”