The seven members of the K-pop group BTS, the first South Korean musicians to top the Billboard charts, must fulfill their mandatory military service, the country’s defence ministry confirmed this week.

By law, able-bodied South Korean men must register to spend about two years in the armed forces, as part of a conscription system seen as crucial to the country’s defence against North Korea. Women are exempt, but can enlist.

K-pop stars are no exception, Lee Nam-woo, an official with ministry of defence, said at a news conference Thursday.

The public has shown significant interest in the government’s consideration of exemptions for popular artists who have contributed to the country’s reputation, he said, but the exemptions have been denied.

All seven members of BTS are in their 20s.

K-Pop stardom luring Japan's youth to Korea Show all 10 1 /10 K-Pop stardom luring Japan's youth to Korea K-Pop stardom luring Japan's youth to Korea Yuuka Hasumi, 17, and Ibuki Ito, 17, from Japan, who want to become K-pop stars, perform at an Acopia School party in Seoul, South Korea. Acopia is a prep school offering young Japanese a shot at K-pop stardom, teaching them the dance moves, the songs and also the language Images Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Miyu Takeuchi, a trainee with the K-pop agency Mystic Entertainment, sings during a training session in Seoul. Takeuchi said it wasn't a difficult decision to leave a 10-year career with a top idol band AKB48 back home in Japan to sign with the K-pop agency Mystic Entertainment in March as a trainee. Even with her experience, she has seven hours of vocal training a day and two-hour dance lessons twice a week, plus early morning Korean lessons. She is not allowed to have a boyfriend but she says she has no regrets, despite the fact there is no guarantee she will make it. "I don't know how long my training period will be, but it has to reach a point where my coaches and management company say 'Miyu, you are a professional!'" Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Yuuka sings a song as she spends time after class, in the Hongdae area of Seoul. She put high school in Japan on hold and flew to South Korea in February to try her chances at becoming a K-pop star, even if that means long hours of vocal and dance training, no privacy, no boyfriend, and even no phone. "It is tough," Hasumi said. "Going through a strict training and taking my skill to a higher level to a perfect stage, I think that's when it is good to make a debut" Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Nao Niitsu, 19, a college freshman from Tokyo, who wants to be a K-pop star, practices dancing to K-pop songs in her room in Tokyo. "I've heard stories about no free time or not being able to do what I want. But, I think all of K-pop stars who are now performing have gone down the same road," said Niitsu Reuters/Kim Kyung Hoon K-Pop stardom luring Japan's youth to Korea Yuho Wakamatsu, 15, who wants to become a K-pop star, adjusts her makeup during a training session in Seoul Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Nao and other children sit on a bus heading for an audition in Seoul Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Yuuka and Ibuki at a street performance in Hongdae area of Seoul Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea Nao chooses her profile picture before an audition in Seoul. During a visit to Seoul paid for by her mother, herself a die-hard BTS fan, Niitsu auditioned for 10 agencies and was accepted by five Reuters/Kim Hong-Ji K-Pop stardom luring Japan's youth to Korea A K-pop applicant performs at an audition in Tokyo Reuters/Kim Kyung Hoon K-Pop stardom luring Japan's youth to Korea Nao and other Japanese children warm up for an audition at a park in Seoul Reuters/Kim Hong-Ji

“As a Korean, it’s natural,” Jin, whose birth name is Kim Seok-jin, said in a CBS News interview in April. “And someday, when duty calls, we’ll be ready to respond and do our best.”

Big Hit Entertainment, a South Korean entertainment company that manages BTS, did not immediately respond to a request for comment Friday.

Athletes and classical musicians have occasionally been granted exemptions if they won gold medals at the Asian Games or any medal at the Olympics or received international awards.

Draft exemptions are highly sought after in South Korea, where more than 230,000 young men each year, usually between the ages of 18 and 28, must interrupt their studies or careers to join the military. However, the defence ministry said fewer than 45 people are exempt every year, according to Reuters.

Tamar Herman, a Billboard journalist who has covered K-pop and the East Asian entertainment business, said the group and their fans are generally aligned and in support of the military rule.

Their K-pop peers have served, so starting a precedent now by exempting BTS would be disruptive, Ms Herman said. It’s also a matter of national pride. Celebrities’ careers have been ruined for trying to evade service, she added.

BTS has not previously said whether its members will stagger their time in the military or all register at once, Ms Herman said.

“There’s this idea that this might put a halt to their popularity, but their fandom is so big, I personally don’t think it will,” Ms Herman said. “Only time will tell.”