it is common since to make the standard age to join the military at a minimum age of 21+
the bottom line is, people who are 17-18-19-20 just truly aren't mature enough for that kind of power.
if 21+ is the basis of alcohol
21+ is the basis of police force
the united states military lets people join at 18 sometimes even in the case of 17 to my understanding. yet look at the combat training and special tactics, that have ALREADY been used against police.
in theory, suppress minors from joining the military. why because all they want to do is fight. and not for the right reasons what so ever. and that in my book is un-American. unless quite possibly having approval. and longer boot camp to mature.