BTS member Suga (File Photo: AP_
All able-bodied men in South Korea must serve at least 18 months in the military and, after a years-long debate about whether BTS deserved an exemption, Jin, the oldest member of the group, enlisted last year, followed by his bandmate J-Hope in April.
"We would like to inform our fans that SUGA has initiated the military enlistment process by applying for the termination of his enlistment postponement," HYBE said in a statement.
"We ask you for your continued love and support for SUGA until he completes his military service and safely returns," it added, without providing further details.
Before the band went on a hiatus in June last year, BTS bagged six No. 1 hits on the Hot 100 chart and all seven members of the boyband have reached the top of the charts with solo tracks, Billboard said.
Since their debut in 2013, BTS have been credited with generating billions of dollars for their country, as well as boosting the image and soft power of South Korea -- now a global cultural powerhouse.
They have been invited to speak at the United Nations, and to meet US President Joe Biden at the White House.
Earlier this year, the chairman of the septet's agency, Bang Si-hyuk, said that making BTS do their military service was slowing the global growth of K-pop.
The global K-pop market "narrows significantly when BTS is taken out", he said, adding "the continuity of a person's career or their value as a national asset is damaged" by enlisting in the military.
South Korea offers exemptions from military service to people including Olympic medal winning athletes and some classical musicians, but K-Pop musicians are not eligible under the existing program.