Not buying software from the US
That's great, if the US is your only adversary. You would have to add the UK, Australia, Canada and various other allies to that no-buy list. And insure that all your hardware is securely shipped directly from the factory with no opportunity for someone to intercept it and alter it. And hope that the factory (probably based in China) has good security to prevent it being bugged there. And hope that maybe China's government isn't willing to cooperate behind the scenes on certain things contrary to public statements that make them seem at odds about most things.
I think avoiding US software is only the tip of the iceberg, if you are an Iran or North Korea trying (for example) to set up centrifuges to purify uranium to weapons grade concentrations. You would probably be better off buying some 90s era PCs from a third world school and installing a fresh copy of Windows 98 on them to operate your equipment. Connect them with unmanaged 100 mbit switches. No worries about getting modern malware on them, or the hardware coming prebugged to target you. Go retro, in other words.
No USB ports means no USB sticks carrying Stuxnet. Probably don't even have to worry about boot sector viruses or TSRs anymore, because no one would be left using floppies except you :)
Biting the hand that feeds IT
