Fair enough. My experience is fairly recent but it might also be a military vs intelligence agency thing. All the classified/SCIF systems I used were networke

Fair enough. My experience is fairly recent but it might also be a military vs intelligence agency thing. All the classified/SCIF systems I used were networked, though the networks were physically segmented and most of the classified systems I used did not have internet access. Whether that counts as "air gapped" in your book I dunno, but I never came across anything like the room out of the original Mission Impossible film where the machine has no network access at all. In fact I question the utility of such a machine.