I think the Ukrainians have shown that FPV drones may be the real threat. If you can take out a tank with one - and there are numerous videos of that happening - there are a lot of much softer targets around. For that matter, most of the better high school first robotics teams could probably build something autonomous that would be a mini-Terminator if they used bullets rather than whiffle balls.

https://youtu.be/8N2bgMSf9HU?si=5R7781clxSrl96gB