Oh noes! Enemy nation state is on the cusp of AI. I know! I will hack/disable the HVAC, that will annoy them for at least a week until they can get back online.
Funny you say that. Back in former life, we built a distributed alarm and monitoring system for AT&T central offices with no single point of failure. So it's like HVAC can be taken offline easily at critical facilities, with backups and backups of backups.