The seven members of BTS - one of the biggest groups in the world - will perform military service in South Korea, their agency announced, ending a long national debate over whether they should be exempt from the rule.

The artists will each serve almost two years in the army. Jin, the group's oldest member, will be the first to change his stage outfit to a military uniform soon after he turns 30 in December, media said. The other six members, born between 1993 and 1997, will follow his example.

The BTS stars are expected to reunite around 2025, according to their management company, Big Hit Music. The decision comes months after BTS announced that the singers were taking a hiatus as a group to focus on solo careers.

All able-bodied South Korean men under the age of 30 must serve in the military for 18 to 21 months — a duty intended to maintain the country's ability to defend itself against a possible attack by North Korea, with which is technically still at war. Some South Koreans, such as musicians and classical dancers who have won medals at the Olympic and Asian Games, are exempt from the rule.

BTS is worth more than $3.54 billion a year to South Korea's economy, according to a 2018 report by the Hyundai Research Institute — a figure equal to the contribution made by 26 medium-sized companies. The institute said BTS is the reason why one in 13 tourists visit South Korea. But all this does not matter when it comes to the army.

Refusal to perform military service is a crime in South Korea and can lead to imprisonment.