Oh, and the snarky 'trained killers' remark is so disingenuous; far more people join the Services in rôles where killing is most definitely not on the agenda.
There ain't no passengers in a fighting unit, you're all there to get the fighting done and if necessary you will pick up a weapon and join the fray (on pain of a charge under Queens Regulations).
Every soldier has to pass his BFT and shooting test every year be he an infantryman, a driver in the logistics corps or a PO in the Galley. I would expect the other services have a similar requirement. What is that if not training young men to fight and kill?