I have faced this dilemma on exercises in the cold war days - do we ask our tradesmen to guard and accept no serviceable aircraft in the morning - or do we work on the aircraft and let the intruders in because the reinforcements for guarding did not arrive?
No point working on aircraft if they are unguarded and no point having military tradesmen (and women) unless they can fight. Civilians can specialise, military are fighting men (and women).