Joining the Military should be an informed, personal choice. Putting recruitment officers in public schools is a direct influence on the mindset of students. The military is an intimidating venture, and having such an intimidating influence at one's school starts to feel like obligation. I believe that, instead, only people ages 18 and up should be subjected in any way to military recruitment campaigns.
No, military recruiting in public schools does not violate international law, because it should be up to the United States whether to recruit for its military in its own public schools. Other institutions and colleges are allowed to come to campus and recruit, so it is only fair that students can learn about educational opportunities in the military as well.