Just a thought on 'effective' defense. Think of us humans as a biological species. In the bigger scheme of things, we must be among the most vulnerable of all species. Not much natural 'force protection' - no armature, etc. Not much 'mobility' - just try outrunning a cheetah. Not very strong when compared to other primates or other much stronger species. Not all that big as you find out when you look in awe at an elephant or a giraffe. No real special weapons like venom, sharp teeth or claws, vicious horns, electric rays or any other types of weapons that nature has invented. And yet, the 'force', the capability bundle we have evolutionarily developed trumps all of these better protected, faster, bigger, intrinsically deadlier species. Might there not be a lesson in that for our defense organizations?
For those interested in this, I recommend this fascinating article in Scientific American.