I really feel for you. My son is a US Marine and leaves next week for Iraq (his first tour), it's very scarry but my faith will keep me strong. He signed up before he graduated, it took a lot of convincing for me to allow that. He's been in for about 3 1/2 years now and has a wife and 22 month old little girl. He loves his country and was determined to be a Marine like his Grandpa, he wouldn't even talk to any other branch. He's had a lot of training, was in Security Force for 2 years and wants to be a police officer when he gets out, the training he's received will go a long way in helping him become one. He's passionate about his job, yes he'll be ready to get out when his time is up (he signed up for 5 years), but he's ready to go over and do his duty. In his mind he hasn't really served his country until he's been over to Iraq like so many before him. If God forbid something happens to him I'll know that it was his choice and where he wants to be and what he wants to be doing. If your son is doing this strictly for the money and has been against the military or the war in Iraq in the past then he should not be joining. He will most likely be deployed and may end up resenting it. He should only do it if he truely wants to serve his country and be ready to do whatever is asked of him. I really hope that you can determine his true motives and guide him from there. Good luck to you and your whole family, I pray that he makes the right decision.
Oh and if he decides to join and they make any promise GET IT IN WRITING