PYEONGCHANG, South Korea—With the beginning of the Olympic torch relay, celebrations surrounding the 2018 Winter Olympics are now officially under way.

But Pyeongchang has a Pyongyang problem.

As unlikely as a military confrontation may be, the North Korean threat is overshadowing efforts to gin up excitement for a Winter Games local officials are pitching as the “Peace Olympics.” Ticket sales for the event in Pyeongchang, just 40 miles from the Demilitarized Zone, are weak, sponsors are sending smaller delegations than in previous Games and foreign officials are expressing safety concerns.

So far, organizers have sold only about 30% of the tickets they targeted to sell world-wide, and less than 20% of the batch earmarked for South Koreans. That’s the slowest start to any modern Games, say close Olympics watchers.

Pyeongchang Olympics mascots Soohorang and Bandabi

In the U.S., the official ticket sales agent, New Jersey-based CoSport, requested only about 18,000 tickets to sell in the first phase, which ended in September, according to Olympic officials in the U.S. and South Korea. It is looking like a Friday night high-school football game at Farrington Field in Fort Worth, Texas, will outdraw the number of Americans buying tickets to Pyeongchang.

The struggles add to concerns among marketers and sponsors that major events like the Olympics may no longer hold public attention like years ago, when the media landscape was less fragmented and viewers had fewer choices. Television ratings for Brazil’s 2016 Summer Olympics were down significantly from previous Games.

Just two cities ultimately bid for the 2022 Winter Games, and after Brazil, Rome and Budapest dropped bids to host the 2024 Summer Games.

The geopolitical and marketing headaches represent a stark contrast with the jubilation South Koreans felt six years ago, when Pyeongchang won the bid for the 2018 Games. Pyeongchang’s win, on its third try, brought tears to one South Korean official, who had called the bid his “destiny.”

It’s a different story today. This week, Japan’s defense minister said the North Korean threat had grown to an “unprecedented, critical and imminent level.” In recent weeks, foreign officials have expressed concern about safety, with France briefly suggesting it might consider skipping the Games if security fears keep growing.

South Korean and International Olympic Committee officials are adamant the February event will be safe and secure. “No one” is expressing doubts the Pyeongchang games will be safe, said Christophe Dubi, the IOC’s Olympic Games executive director.

Transforming Pyeongchang Into an Olympic City Ticket sales for the Winter Games in Pyeongchang, South Korea, have been slow, but the country has achieved key milestones in fundraising and venue construction, which is almost finished. The ski jump stadium that will be used at the Pyeongchang Olympics. It is currently being used by a professional soccer team. Jun Michael Park for The Wall Street Journal 1 of 11 • • • • • 1 of 11 Show Caption The ski jump stadium that will be used at the Pyeongchang Olympics. It is currently being used by a professional soccer team. Jun Michael Park for The Wall Street Journal

But a bigger issue is whether enough people will show up. The sluggish ticket sales raise questions about the IOC’s strategy of holding three consecutive Games in Asia to capture interest there, though the next two Games—in Tokyo in summer 2020 and Beijing in winter 2022—will at least be in larger population centers.

All three will force organizers to schedule marquee events in Asia’s morning to show them live in prime time in the U.S., where media rights fetch the highest fees. Figure skating, a fan favorite, in Pyeongchang will be held in the morning.

Meanwhile, the qualification of a North Korean figure-skating duo—the only athletes from the country so far known to be participating in Pyeongchang—has been seen as an insurance policy for the 2018 Games.

The IOC and South Korean organizers say they believe they can achieve their goal of selling 90% of tickets before the Games begin on Feb. 9. Experts say sales historically pick up once the torch relay arrives in the host country, which will be Nov. 1 for these Games. The Pyeongchang Olympic flame was officially lighted at a ceremony Tuesday in Olympia, Greece.

For Vancouver’s 2010 Winter Games, one of the most successful Olympics ever, roughly two-thirds of events were sold out—with waiting lists—13 months before the opening ceremony.

“South Koreans tend to be very late ticket buyers,” said Eom Chan-wang, director general of marketing for the Pyeongchang Organizing Committee for the 2018 Olympics, a group known as Pocog. He said that over 80% of domestic ticket sales occurred in the final two months before other major sports events in South Korea in recent years.

A bobsled-like waterslide in Seoul was part of a promotion in August to build excitement for the Winter Games. Photo: Lee Jin-man/Associated Press

Still, South Korea has achieved key milestones in fundraising and Olympic venue construction, which is almost finished.

Pyeongchang is relatively unknown compared with some Winter Olympics destinations. With a population of just 43,000, three hours by car from Seoul, Pyeongchang is the smallest city to host the Winter Games since Norway’s Lillehammer in 1994. Those games were an easy sell—Norwegians are madly obsessed with the Winter Games.

Pyeongchang “never had any real sex appeal,” said Rob Prazmark, a former consultant to the IOC who has worked with companies on Olympics marketing since the mid-1980s. “Not a lot of people have heard of [it].”

The alpine resort town is known for its premium local beef and dense forest trails.

Despite local officials’ claim that over 42,000 rooms will be available within an hour’s ride of Olympics venues, a recent English-language search online found few available options during the Olympics period.

“There are a lot of broken promises to what was originally committed on the bid to what’s now being delivered,” said Michael Payne, a former IOC marketing director, pointing to a lack of progress on accommodations and other services.

Many property owners aren’t accustomed to using international booking sites, said an official in the local provincial government, which is responsible for overseeing accommodations for the Games. The province has teamed up with travel website Booking.com to help business owners to register on the site and is looking to work with more partners.

Among fans who are going, many are staying almost 100 miles away near Incheon International Airport or in Seoul, where more rooms are available for lower prices.

Andrew Pham from Spokane, Wash., said he booked a hotel near the airport. He plans to travel back and forth each day on a newly built bullet train that promises to get him to Olympic venues within two hours.

For Ron Isbell, a retired accountant from Arlington, Texas, who has attended every Olympics since 1996, high prices are likely to make Pyeongchang his most expensive Games ever. He said he hasn’t found hotels within the $150 per night budget he allocated for other recent Olympics.

In the U.S., officials and executives connected with the Games said excitement and sales have been slow to build.

Given travel expense and language and cultural barriers, “it should not be surprising that our market-to-market tickets sales for Pyeongchang will be closer to those for Sochi”—the Russian host of the 2014 Winter Games—“than to those for Vancouver,” said Michael Kontos, spokesman for CoSport.

CoSport declined to provide exact figures for Pyeongchang sales, and U.S. ticket sales for Sochi haven’t been disclosed.

General Electric Co., a sponsor, is planning to send a smaller contingency from its U.S. headquarters to Pyeongchang, people familiar with the company’s plans said.

Knowing that accommodations would be difficult, NBCUniversal, which owns U.S. media rights, decided to bring customers on a skiing vacation in Jackson Hole, where it will hold watch parties.

Lisa Baird, chief marketing officer for the U.S. Olympic Committee, said Games excitement isn’t tangible yet in part because marketing campaigns from NBCUniversal and other sponsors haven’t fully kicked in.

“It’s been slow to date, but I think we are going to see the momentum build now with the snow,” Ms. Baird said last month at a USOC conference in Park City, Utah.

NBC, which has committed nearly $12 billion since 2011 to lock up rights to the Games from 2014 through 2032, has yet to announce how much​ commercial time is still available for purchase for its telecasts. Its promotional campaign so far largely has been limited to the little-watched Olympic Channel and social media.

In a statement, an NBC spokesman said internal tracking of Olympics awareness and excitement was “encouraging.”

A tourist takes a picture of Soohorang and Bandabi, the mascots of the Pyeongchang Winter Olympic Games and Paralympics. Photo: Jun Michael Park for The Wall Street Journal

Organizers had hoped China, the next Winter Olympics host, would help drive ticket sales to South Korea. But China’s official Olympics ticket vendor initially requested just 3,000 tickets.

“The situation in China has been tense since the Thaad issue,” said Pocog’s Mr. Eom, referring to the U.S. missile defense system installed in South Korea this year that fueled diplomatic strife between Seoul and Beijing.

In South Korea, about 85% of South Koreans expressed a preference to watch the Olympics on television rather than in Pyeongchang, according to an April government survey.

That has fueled speculation organizers might have to scramble to fill seats. A Seoul-based sports events manager involved in planning South Korea’s 2011 World Championships in Athletics, a track and field competition, said school children were mobilized to occupy some seats and that many tickets were sold to government officials.

Mr. Eom of Pocog remains confident that Pyeongchang will sell enough tickets, but added that organizers are also devising a plan to fill seats in case ticket holders don’t show up at events.

“We have to fill the venues,” said Lee Hee-beom, chief executive of Pocog’s organizing committee, in an interview. “NBC has asked us; broadcasters have asked us to fill the stadiums.”

—Noemie Bisserbe and Andrea Thomas contributed to this article.