How do i convince my best friend not to join the army?

My best friend and maybe a little more than that wants to join the army when he turns 18. He turns 18 in about 6 months. And I don't want him to join. No one does. He says he wants to join because there is nothing else for him where we live and that it is the only thing left for him. But we all disagree. I am really scared to let him go. What if I never see him again? He is wanting to be the one who disarms bombs and is out in a mine field. I just don't think its that good of an idea. What should I do? I'm really scared.