If your threat model is the same as an intelligence service, which it basically would if in effect you wanted to protect against state intelligence services, th

If your threat model is the same as an intelligence service, which it basically would if in effect you wanted to protect against state intelligence services, then you would need to follow similar procedures. AFAIK, it's a common practice to have critical systems disconnected from the internet or external networks and located in rooms protected against human intrusion (duh) but also against remote sensing, which these days includes pretty much anything (RF, sound, light, etc). You'd also need to take special measures to avoid equipment from being tampered with before it reaches you. I read articles that the Russians were banning computers altogether in some circumstances and using typewriters instead. But of course if this is indeed "threatening" you'd be as likely to have an 'unfortunate accident' in any case.