https://www.mercurynews.com/2019/11/21/bts-cant-get-out-of-military-service-south-korea-says/

(CNN) — K-pop megastars BTS will have to serve their compulsory military service, after South Korea’s Defense Ministry announced that it would not be issuing a change to its exemption rules.

South Korea has compulsory conscription, and almost all healthy men are required to serve in the army. Some performers and sports players can get exemptions  — but apparently world-famous K-pop stars do not.