To me, that's what the U.S. Army Marksmanship Unit is doing. Every year it holds a clinic for children aged 9 to 18. The clinic is free and scholarships are available for those needing air fare and accommodations. The clinic focuses on practical shooting, a sport that simulates combat shooting conditions using assault rifles. This is not the only opportunity of this kind available for kids. There is the United States Practical Shooting Association (USPSA) which holds hundreds of contests held around the country.
I can understand training kids to use guns. But 9 years old? Assault rifles? Simulating combat conditions?