For members of the United States military, conduct is governed by the military’s own law, the Uniform Code of Military Justice (UCMJ). For military members, the crime of rape can be (and has been) punished by death.
The age of consent for members of the military is 16 years of age. This means that a member of the military who has sex with a person under the age of 16 is committing a crime.
Depending on whether the sex is consensual or not, the crime can be punishable by death. If the sex is consensual, the crime is known as "carnal knowledge" and is not punishable by death. However, if the sex is nonconsensual, it is considered "rape" and can be punishable by death.
The UCMJ section prohibiting sex with persons below the military age of consent is very brief. The law does not list a specific punishment for the crime, but only states "as the Court-Martial may direct." This probably means for consensual sex that any punishment short of death can be imposed, including dishonorable discharge and prison time.
Unlike many state laws, the UCMJ does not have any provision making exceptions for parties who are close to the same age. For example, if an 18-year-old serviceman has sex with a 15 ½ -year-old girl, he is committing a crime even if she consents. However, the day she turns 16 years old, it is legal for them to have sex.
The UCMJ allows mistake of fact to act as a defense in these cases. If the victim is, in fact, over the age of 12, and the offender reasonably believed that he or she was 16 or older, then this fact is a valid defense and the military member will not be punished.
Being charged with the crime of having sex with an under aged minor is a very serious matter. The punishment for this crime is much more severe in the military courts than in the United States criminal courts. An attorney experienced in military law can represent you and help you reduce your punishment or even your charges dismissed, therefore it may be advisable to retain a civilian criminal defense attorney.