Hi C.,
I have 2 sons that are now young men and an almost 14yr old son and 2 11yr old daughters. So I understand. My oldest is in the military and has been for 7 yrs now, I understand that too (though he's 24 and not married).
I say punishment is needed depending on the "crime". Perhaps in this surcomstance, a warning that more severe action will be taken if this or anything like this is ever to happen again along with us (Mom and Dad) loosing trust in you. Starting first with things he values like taking away the cell phone and or ipod (if he has one), sleep-overs with friends, no going over to friends houses, or if you allow going to outside places to "hang out", that could be cut out too. What you could start is if he owns a cell phone, ipod-touch or any other device that needs to be charged. Tell him that he will have to keep all of his things that need to charged up down in the dining room by 9pm to charge over night. This way you (as parents) will have controle of it and you know he won't be getting or recieving calls at all hours and you can scroll through it and monitor what he is up to. It's what WE have to do sometimes to ensure our kids are making the right choices. He also needs to understand that he is an example to his younger brother as well (though he doesn't want to hear that, I'm sure). He does need to be reminded that just like us parents who have to be a good example to you (you talking to your son), you need to be a good example to your younger brother. Maybe alittle guilt will help too--who knows, it can't hurt too much!--ha ha!
Just make sure you re-assure him how much you love him and you never want to be in a position to not have faith in him or not trust him.
Good luck.