Sorry, I was away from Lemmy for a while.

A bunker.

Well, do you have a favourite bunker siege? Of course not, there aren’t any. If the enemy is upon you, a bunker won’t help for long; they’ll dig in or drop grenades down your ventilation or something. Or destroy all access points turning it into a kind of tomb, like we’ve seen the US do in Iran.

Meanwhile, a castle was a thing you hide inside, to wait out an enemy right next to you, because there was no good way to take it on with muscle-powered weapons and no flight. They’re just fundamentally different tools filling completely different roles. While both are heavily built stone things, the resemblance is fairly superficial.

But a lot of the tactics already exist

It’s two very different things to say “exist” and “have been planned for, organised for and trained in”. Aspects of drone warfare will resemble some historical thing, sure, but that doesn’t change much from an NCO’s perspective.

The tactics and tech to defend mobile units against air threats (including drones) existed for many decades and were just neglected in years where asymmetric warfare was more relevant.

A drone in the air littoral is a very different from from a plane in the blue skies. The Gepards were “white elephants” because they’re useless against any modern manned aircraft - they fly either too high, or nape-of-the-earth, preventing a good shot. Maybe some officer somewhere expected attritable drones to arrive, and make them worth something again, but for most people, it was a black swan event.

Anti-air missiles, which are relevant to that problem, were never sent anywhere.

The ill advised swing to “unconventional warfare” (read: mostly not war) happened, that’s true, though. It was just one aspect of how complacent the West got after the Cold War ended.