I believe the main difference between 'natural caused hazard' or failure and intentionally
made offense by adversary is of course the objective, but consuming defensive resources, a tactical depth in other words.
Critical infrastructure can be seen within this article as defensive infrastructure or a support structure for decision making.
Most nature caused issues are recoverable by changing physical parts of devices, enabling electric grid again etc. - whilst mailicous adversary might want to delay such effort in means of consuming resources. That being said/written, contigency planning is key element to provide survivality.
Just keep in mind that the data controlling most of the critical infrastructure may need to be reconstructured and all computerized interfaces may be just unusable.
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