Demonstration? Autonomous AI self-targeting swarm drones with lethal munitions are here, taking orders in quantity NOW.

A group calling itself StratoEnergetics is on a campaign to raise awareness about autonomous drone based weapon systems.

Very nicely presented.

The technology described is completely achievable today, though in my opinion, would likely suffer from some bugs and not quite achive 100% in targeting accuracy (oops).

https://boingboing.net/2017/11/15/stratoenergetics-introduces-ne.html

And you'll notice legit defense industry sites picking up the story and running with it…

https://civil-defence.ca/2018/09/micro-armed-killer-drones-with-autonomous-artificial-intelligence/