Help!! Cousin wants to go into the army??

Okay, my cousin, who is living with us and is basically my brother, (long story), wants to join the army, but me and my mother are afraid that when he gets there, he will be sent to Iraq and very possibly get killed. He is only 17 years old and does not know what he wants. i am only 13 and i am more rational than he is. he just wants to go because he says there is nothing for him here. he tells me to stay out of it, and that i don't know what im talking about, but i do. Gosh, i have a lot of respect for him, and i will stay out of it somewhat, but it is really hard. if he wanted to go and make this huge decision because he is truly devoted to it and really wants to go, i would understand. but that is hardly the case. it's all a game to him, and he doesn't want to hear about it. he is so hardheaded and thinks that he knows everything, but he still has a long way to go.. Is there anyway we can convince him not to join?? SORRY THIS IS SO LONG. THANKS GUYS.