If you get charged with illegal possession of alcohol because you are an underage person (under 21), then it may be an issue for the military court. You need to check with an attorney who specializes in military law to determine if this is a matter that a) must go before a military court because of your military status and b) if you or the court must report the charge to your commanding officer. By speaking to counsel and based on your previous (if any) criminal history, you may be able to have the charges dismissed or qualify for some sort of alternative conviction wherein you must stay out of trouble for a certain amount of time and the charges will be dismissed.