The oldest member of K-pop phenomenon BTS will begin his military service on December 13 and become the band’s first member, local media reported on Thursday.

All able-bodied South Korean men under the age of 30 are required to serve about two years of military service, largely because the country is technically still at war with nuclear-armed North Korea.

That means the age limit for 29-year-old Jin, senior member of the hugely popular septet, is fast approaching.

He will begin his mandatory five-week training in Yeoncheon in Gyeonggi Province before being assigned to a “frontline unit,” Yonhap News Agency reported, citing military and industry sources.

The singer had previously hinted on social media that he was deployed to the front lines.

The news left fans stunned and emotional, with some even expressing concern for Jin’s safety.

“My heart literally sank when I read that he’s deployed to the front lines,” one fan tweeted, adding, “This military thing that’s been surrounding BTS for years is NEVER really my business until now. Why at the front? Why?”

Another fan said: “I can’t help but think they’re sending him to the harshest, scariest place as punishment.”

BTS is credited with generating billions for the South Korean economy and their label has seen profits jump despite fewer concerts during the coronavirus pandemic.

But the prospect of mandatory military service has long hung over K-pop superstars, sparking a year-long debate in South Korea about whether they deserve exemptions — which are granted to classical musicians and Olympic medalists, for example.

Their agency announced last month that band members would complete their mandatory military service, beginning with Jin.

Seoul’s defense minister had said in August that BTS may still be allowed to hold international concerts and prepare for international concerts even if they take on military duties.