Mostly, people put focus cybersecurity on critical infrastructure. We must not forget the cybersecurity for supporting systems are equally important as they are also network connected for information exchange or control from the control center. These systems automate protection for the core system. Examples are those commonly known like facility management (or FM such as fire fighting, CRAC, access control, UPS), SIS (Safety Instrumented Systems).
If these systems fail, it will impact to the core systems. There is recent incident for cyber attack on SIS. Imagine, if the FM fails, the information processing facility will fail too. More severe impact is the SIS failure, it will affect environment or human safety.