The agency wrote,

"Hello, this is DSP Media.
We are here to deliver news regarding Jaehyung of A-JAX. 
Jaehyung will be enlisting for his mandatory military service at the Nonsan training center on this coming 8th.
He will complete 4 weeks of basic soldier training and then carry out 23 months of service as a public service personnel. 
Because he had mentioned that he wanted to enlist quietly, there will be no separate event on the day of his enlistment.
Please give your support to Jaehyung, who will be halting his team activities to carry out his service.
We also ask that you look forward to and give your love to A-JAX's continued activities. Thank you."

Jaehyung also reached out to his fans to tell them how much he'll miss them through a handwritten letter. 

He posted on Twitter, "Hello. This is Jaehyung. I'm sorry I'm suddenly delivering the news of my enlistment. After much thinking, I've come to deliver the news late to you all. I've been so thankful and happy as I recalled back on our memories and the love we've received. Because I always had you, who stayed by my side and protected me, I was able to always laugh and shed tears of happiness. Whether it'll feel like a short or a long period of time, I think I'll miss you all the most. I will return as a more matured person after learning about many new things. Like a tree, I will always be here thinking of you first with a humble attitude. Spend a healthy and warm winter and happy new year. I love you. - Sincerely, Jaehyung"