It also acted as a starting gun for every other country on earth to create and/or massively expand their cyber warfare capabilities. Sparking a new arms race for the 21st century, normalizing acts of (cyber) aggression against foreign infrastructure during peacetime.
Assuming the conventional wisdom about the event is accurate:
A state military attacking a perceived threat to the national security of that state (while at the same time doing its damndest to make sure nobody knew about it) is pretty clearly outside the definition of terrorism. It fits squarely into espionage / warfare.
None of the terrorism boxes get ticked. It wasn't a splashy, overt thing meant to instill fear. It wasn't carried out against emotionally-charged targets attempting to incite, nobody claimed credit, etc.
Everything adverse that happens is not terrorism. The term has kinda worn itself out, which is bad, because that word invokes a whole bunch of executive power shifts.