some very simple predictive index assessments that can be given in the hiring process. the navy created one for WW2 that allowed them to decide where on a plane you would be seated. If you came up as someone that would personalize dropping a bomb, you wouldn't have that job. These tests are not expensive to administer and would nearly guarantee someone could pull the trigger if necessary. I'm sure the military still uses these today to decide career paths...
(btw i am basing this off my assumption that a predictive assessment was not part of the hiring process)
All missileers (people that sit on the launch console) must go through extensive background checks and questioning to determine if they are fit to be a missileer and in fact, can do the job if called on.