My personal opinion and speaking from experience
It is stupid to be part of any police or military. You cannot quit once you sign up. If they send you to certain deaths, you have to go. Saying no also means they put you to death.
Imagine if you are police and your wife and children happen to participate in some thing that the power says is not allowed. You are asked to shoot on sight. If you are military and they want you to kill innocent women and child, you have to do it or else face the firing squad.
Old people use to say. Good sons dont join police (some Cantonese saying -hou cai mo tong cai)