>>712651274
That depends on many factors.
The fast flying object typically has a significant IR signature, and the real trick is to intercept it quickly enough before it get to you.
A stationary drone in the treeline has a very low IR signature, but you need self/wire-guided ones to no have a detectable EM signature.
If you are only detecting using the visual spectrum, you need seriously quick and efficient AI.
The real difficulty will be making the system + turrets (ideally multiple of them sharing position from multiple angle) cheap enough.
And despite me posting this pic, I expect future AI to be well-trained enough to immediately detect such treachery, contact an human, or kill the target once it make the slightest mistake.
